Sulfopolyester binders

ABSTRACT

A versatile binder comprising at least one or more sulfopolyesters is provided. These sulfopolyester binders can enhance the dry tensile strength, wet tensile strength, tear force, and burst strength of the nonwoven articles in which they are incorporated. Additionally, the water permeability of these binders can be modified as desired by blending different types of sulfopolyesters to produce the binder. Therefore, the binder can be used in a wide array of nonwoven end products and can be modified accordingly based on the desired properties sought in the nonwoven products.

RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application Ser.No. 61/405,312, filed on Oct. 21, 2010, the disclosure of which isincorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to sulfopolyester binders for use innonwoven articles.

2. Description of the Related Art

Nonwoven articles are found throughout the consumer marketplace.Nonwoven articles, which are generally made up of microfibers and/ornanofibers, are generally produced using a wet-laid or dry-laid process.Various methods or compositions are generally utilized in order to holdthe fibers within a nonwoven article together. For example, it is knownthat nonwoven articles can be held together by (1) mechanical fibercohesion and interlocking in a web or mat; (2) various techniques offusing of fibers, including the use of binder fibers; (3) use of abinding resin; (4) use of powder adhesive binders; and/or (5)combinations thereof. The fibers are often deposited in a random manner,although orientation in one direction is possible, followed by bondingusing one of the methods described above.

Unfortunately, many of the methods or compositions mentioned above lackversatility in their methods or properties, thus limiting theirapplication to specific end uses. In addition, many of the bindercompositions utilized above lack the ability to be modified in order tofit a wide array of end use products. For example, many binders have afixed water permeability which cannot be significantly modified withoutsacrificing the integrity of the binder composition. Thus, these bindersare limited in scope to certain nonwoven articles that can utilize theirnarrow range of water permeability properties.

Accordingly, there is a need for a versatile binder that is capable ofbeing optimized in accordance with the desired end uses of the nonwovenarticle.

SUMMARY

In one embodiment of the present invention, there is provided a nonwovenarticle comprising a plurality of thermoplastic polycondensate fibersand a sulfopolyester binder. The thermoplastic polycondensate fibersmake up at least 10 weight percent of the total fiber content of thenonwoven article, whereas the sulfopolyester binder makes up at least 1weight percent and not more than 40 weight percent of the nonwovenarticle. The nonwoven article further comprises a plurality of syntheticmicrofibers having a length of less than 25 millimeters and a minimumtransverse dimension of less than 5 microns, wherein the syntheticmicrofibers make up at least 1 weight percent of the nonwoven article.

In another embodiment of the present invention, there is provided awet-laid process to produce a bound nonwoven article. The first step ofthe process involves a) producing multicomponent fibers comprising atleast one water dispersible sulfopolyester and one or more waternon-dispersible polymers immiscible with the sulfopolyester. Themulticomponent fibers can have an as-spun denier of less than 15 dpf.The next step b) involves cutting the multicomponent fibers into cutmulticomponent fibers having a length of less than 25 millimeters. Thenext step c) involves contacting the cut multicomponent fibers withwater to remove the sulfopolyester thereby forming a wet lap comprisingcut water non-dispersible fibers, which are formed of a thermoplasticpolycondensate. The next step d) involves transferring the wet lap to awet-laid nonwoven zone to produce an unbound nonwoven article. The finalstep e) involves applying a binder dispersion comprising at least onesulfopolyester to the nonwoven article.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present invention are described herein with referenceto the following drawing figures, wherein:

FIGS. 1 a, 1 b, and 1 c are cross-sectional views of threedifferently-configured fibers, particularly illustrating how variousmeasurements relating to the size and shape of the fibers aredetermined;

FIG. 2 is a cross-sectional view of nonwoven article containing ribbonfibers, particularly illustrating the orientation of the ribbon fiberscontained therein;

DETAILED DESCRIPTION

The present invention provides versatile binders comprising at least onesulfopolyester that can increase the strength and integrity of thenonwoven in which it is incorporated.

The binder of the present invention comprises at least onesulfopolyester. The sulfopolyesters utilized in the binders of thepresent invention can contain substantially equimolar proportions ofacid moiety repeating units (100 mole percent) to hydroxy moietyrepeating units (100 mole percent). In one embodiment, thesulfopolyesters useful for the binders of the present invention cancomprise repeating units of components (a), (b), (c) and (d) as follows,wherein all stated mole percentages are based on the total of all acidand hydroxy moiety repeating units being equal to 200 mole percent:

(a) at least 50, 70, or 80 mole percent and/or not more than 99, 96, or94 mole percent isophthalic acid,

(b) at least 1, 4, or 6 mole percent and/or not more than 50, 30, or 20mole percent 5-sulfoisophthalic acid,

(c) at least 20, 35, or 45 mole percent and/or not more than 95, 85, or80 mole percent 1,4-cyclohexanedimethanol; and

(d) at least 5, 15, or 20 mole percent and/or not more than 80, 65, or55 mole percent diethylene glycol and/or ethylene glycol.

In one embodiment of the present invention, the binders can comprise ablend of at least a first sulfopolyester and a second sulfopolyester.The first and second sulfopolyesters can comprise different amounts ofsulfomonomer, such as 5-sulfoisophthalic acid, and/or different amountsof a hydrophobic glycol, such as 1,4-cyclohexanedimethanol. The amountof sulfomonomers in the sulfopolyesters is important because it greatlyinfluences the water-permeability of the sulfopolyester. In oneembodiment, the first sulfopolyester is hydrophilic and the secondsulfopolyester is hydrophobic. An example of a hydrophilicsulfopolyester that can be useful as a binder is Eastek 1100® byEASTMAN. Likewise, an example of a hydrophobic sulfopolyester useful asa binder includes Eastek 1200® by EASTMAN. These two sulfopolyesters maybe blended accordingly depending on the desired water-permeability ofbinder. Depending on the desired end use for the nonwoven article, thebinder may be either hydrophilic or hydrophobic.

When the binder comprises a blend of at least a first sulfopolyester anda second sulfopolyester, the first sulfopolyester can comprise repeatingunits of components (a), (b), (c) and (d) as follows, wherein all statedmole percentages are based on the total of all acid and hydroxy moietyrepeating units being equal to 200 mole percent:

(a) at least 70, 75, or 80 mole percent and/or not more than 90, 88, or86 mole percent isophthalic acid,

(b) at least 10, 12, or 16 mole percent and/or not more than 30, 25, or20 mole percent 5-sulfoisophthalic acid,

(c) at least 25, 35, or 45 mole percent and/or not more than 70, 60, or55 mole percent 1,4-cyclohexanedimethanol; and

(d) at least 30, 40, or 45 mole percent and/or not more than 75, 65, or55 mole percent diethylene glycol and/or ethylene glycol.

Likewise, the second sulfopolyester can comprise repeating units ofcomponents (a), (b), (c) and (d) as follows, wherein all stated molepercentages are based on the total of all acid and hydroxy moietyrepeating units being equal to 200 mole percent:

(a) at least 80, 85, or 88 mole percent and/or not more than 98, 96, or93 mole percent isophthalic acid,

(b) at least 2, 4, or 7 mole percent and/or not more than 20, 15, or 12mole percent 5-sulfoisophthalic acid,

(c) at least 40, 50, 60 mole percent and/or not more than 95, 85, or 80mole percent 1,4-cyclohexanedimethanol; and

(d) at least 5, 15, or 20 mole percent and/or not more than 50, 40, or30 mole percent diethylene glycol and/or ethylene glycol.

The use of the sulfopolyester binder of the instant invention mayenhance multiple properties of the nonwoven article. For example, when asulfopolyester binder is utilized, the nonwoven article can exhibit adry tensile strength greater than 1.5, 2.0, 3.0, or 3.5 kg/15 mm; a wettensile strength greater than 1.0, 1.5, 2.0, or 2.5 kg/15 mm; a tearforce greater than 420, 460, or 500 grams; and/or a burst strengthgreater than 50, 60, or 70 psig. Furthermore, depending on the nature ofthe water permeability of the sulfopolyester binder used, the nonwovenarticle can exhibit a Hercules Size of less than 20, 15, or 10 secondsand/or greater than 5, 50, 100, 120, or 140 seconds.

The sulfopolyester binders of the instant invention exhibit excellentadhesiveness to thermoplastic polycondesate materials. Suchthermoplastic polycondensate materials can include polyesters (e.g.,polyethylene terephthalate homopolymer, polyethylene terephthalatecopolymer, polybutylene terephthalate, and polypropylene terephthalate)and polyamides (e.g., nylon 6 and nylon 66).

The nonwoven articles of the instant invention can comprise asulfopolyester binder as described above, a plurality of thermoplasticpolycondensate fibers, and a plurality synthetic microfibers with alength of at least 0.25, 0.5, or 1.0 millimeters and/or less 25, 10, or2 millimeters and a minimum transverse dimension of less than 5 microns.In another embodiment, the synthetic microfibers have a length of atleast 0.2, 0.5, or 1.0 millimeters and/or less 10, 5, or 2 millimetersand a minimum transverse dimension of less than 5 microns. Thethermoplastic polycondensate fibers can make up at least 10, 20, 30, 40,50, or 60 weight percent of the total fiber content of the nonwovenarticle, while the sulfopolyester binders can make up at least 1 weightpercent and not more than 40 weight percent of the nonwoven article.Typically, the sulfopolyester binder can make up at least 1, 2, 3, 4, 5,or 7 weight percent of the nonwoven article and/or not more than 40, 30,20, 15, or 12 weight percent of the nonwoven article.

In one embodiment, the synthetic microfibers are formed from athermoplastic polycondensate material so that the synthetic microfibersmake up at least a portion of the thermoplastic polycondensate fibers inthe nonwoven article. For instance, the synthetic microfibers can makeup at least 5, 10, or 20 weight percent and/or not more than 90, 80, or70 weight percent of the thermoplastic polycondensate fibers in thenonwoven article. In one embodiment, the synthetic microfibers make upat least 1, 3, 5, 10, or 20 weight percent of the nonwoven article. Inanother embodiment, the synthetic microfibers can comprise short-cutwater non-dispersible microfibers.

The term “microfiber,” as used herein, is intended to denote a fiberhaving a minimum transverse dimension that is less than 5 microns. Asused herein, a “nonwoven article” is defined as a web made directly fromfibers without weaving or knitting operations. As used herein, “minimumtransverse dimension” denotes the minimum dimension of a fiber measuredperpendicular to the axis of elongation of the fiber by an externalcaliper method. As used herein, “external caliper method” denotes amethod of measuring an outer dimension of a fiber where the measureddimension is the distance separating two coplanar parallel lines betweenwhich the fiber is located and where each of the parallel lines touchesthe external surface of the fiber on generally opposite sides of thefiber. FIGS. 1 a, 1 b, and 1 c depict how these dimensions may bemeasured in various fiber cross-sections. In FIGS. 1 a, 1 a, and 1 c,“TDmin” is the minimum transverse dimension and “TDmax” is the maximumtransverse dimension.

The water non-dispersible microfibers also produced by this processcomprise at least one water non-dispersible synthetic polymer. Dependingon the cross section configuration of the multicomponent fiber fromwhich the microfiber is derived from, the microfiber can have anequivalent diameter of less than 15, 10, 5, or 2 microns; a minimumtransverse dimension of less than 5, 4, or 3 microns; an transverseratio of at least 2:1, 6:1, or 10:1 and/or not more than 100:1, 50:1, or20:1; and/or a length of at least 0.1, 0.25, 0.5, or 1.0 millimetersand/or not more than 25, 12, 10, 6.5, 5, 3.5, or 2.0 millimeters. Allfiber dimensions provided herein (e.g., equivalent diameter, length,minimum transverse dimension, maximum transverse dimension, transverseaspect ratio, and thickness) are the average dimensions of the fibers inthe specified group.

The microfibers of the present invention can be advantageous in thatthey are not formed by fibrillation. Fibrillated microfibers aredirectly joined to a base member (i.e., the root fiber and/or sheet) andhave the same composition as the base member. In one embodiment, lessthan 50, 20, or 5 weight percent of the microfibers are directly joinedto a base member having the same composition as the microfibers.

In particular, the sulfopolyester binders produced from this process maybe used to produce a wide variety of nonwoven articles including filtermedia (e.g., HEPA filters, ULPA filters, coalescent filters, liquidfilters, desalination filters, automotive filters, coffee filters, teabags, and vacuum dust bags), battery separators, personal hygienearticles, sanitary napkins, tampons, diapers, disposable wipes (e.g.,automotive wipes, baby wipes, hand and body wipes, floor cleaning wipes,facial wipes, toddler wipes, dusting and polishing wipes, and nailpolish removal wipes), flexible packaging (e.g., envelopes, foodpackages, multiwall bags, and terminally sterilized medical packages),geotextiles (e.g., weed barriers, irrigation barriers, erosion barriers,and seed support media), building and construction materials (e.g.,housing envelopes, moisture barrier film, gypsum board, wall paper,asphalt, papers, roofing underlayment, and decorative materials),surgical and medical materials (e.g., surgical drapes and gowns, bonesupport media, and tissue support media), security papers (e.g.,currency paper, gaming and lottery paper, bank notes, and checks),cardboard, recycled cardboard, synthetic leather and suede, automotiveheadliners, personal protective garments, acoustical media, concretereinforcement, flexible perform for compression molded composites,electrical materials (e.g., transformer boards, cable wrap and fillers,slot insulations, capacitor papers, and lampshade), catalytic supportmembranes, thermal insulation, labels, food packaging materials (e.g.,aseptic, liquid packaging board, tobacco, release, pouch and packet,grease resistant, ovenable board, cup stock, food wrap, and coated oneside), and printing and publishing papers (e.g., water and tearresistant printing paper, trade book, banners, map and chart, opaque,and carbonless). In one embodiment, the nonwoven article is selectedfrom the group consisting of a battery separator, a high efficiencyfilter, and a high strength paper.

In one embodiment, the nonwoven article can comprise the syntheticmicrofibers in amount of at least 20, 40, or 50 weight percent and/ornot more than 90, 85, or 80 weight percent and the sulfopolyester binderin an amount of at least 1, 2, or 4 weight percent and/or not more than40, 30, or 20 weight percent. In this embodiment, the nonwoven articlemay be a battery separator, a high efficiency filter, or a high strengthpaper.

In one embodiment, the nonwoven article can comprise the syntheticmicrofibers in amount of at least 1, 3, or 5 weight percent and/or notmore than 25, 20, 15, or 10 weight percent and the sulfopolyester binderin an amount of at least 1, 2, or 4 weight percent and/or not more than40, 30, or 20 weight percent. In this embodiment, the nonwoven articlemay be a paperboard or cardboard.

In one embodiment of the invention, a process is provided for producinga nonwoven article with the sulfopolyester binder of the presentinvention. The process can comprise the following steps:

(a) spinning at least one water dispersible sulfopolyester and one ormore water non-dispersible synthetic polymers immiscible with thesulfopolyester into multicomponent fibers, wherein the multicomponentfibers have a plurality of domains comprising the water non-dispersiblesynthetic polymers whereby the domains are substantially isolated fromeach other by the sulfopolyester intervening between the domains;wherein the multicomponent fiber has an as-spun denier of less thanabout 15 denier per filament; wherein the water dispersiblesulfopolyester exhibits a melt viscosity of less than about 12,000 poisemeasured at 240° C. at a strain rate of 1 rad/sec; and wherein thesulfopolyester comprises less than about 25 mole percent of residues ofat least one sulfomonomer, based on the total moles of diacid or diolresidues;

(b) cutting the multicomponent fibers of step a) to a length of lessthan 25, 10, or 2 millimeters, but greater than 0.1, 0.25, or 0.5millimeters to produce cut multicomponent fibers;

(c) contacting the cut multicomponent fibers with water to remove thesulfopolyester thereby forming a wet lap of water non-dispersiblemicrofibers comprising the water non-dispersible synthetic polymer;

(d) subjecting the wet lap of water non-dispersible microfibers to awet-laid process to produce the nonwoven article; and

(e) applying a sulfopolyester binder dispersion to the nonwoven articleand drying the nonwoven article and binder dispersion thereon.

In another embodiment, the multicomponent fibers in step b are cut to alength of less than 10, 5, or 2 millimeters, but greater than 0.2, 0.5,or 1 millimeter.

In one embodiment of the invention, at least 1, 3, 5, 20, 30, 40, or 50weight percent and/or not more than 90, 75, 60, 25, 20, 15, or 10 weightpercent of the nonwoven article comprises the water non-dispersiblemicrofiber.

The sulfopolyester binder dispersion may be applied to the nonwovenarticle by any method known in the art. In one embodiment, the binderdispersion is applied as an aqueous dispersion to the nonwoven articleby spraying or rolling the binder dispersion onto the nonwoven article.In another embodiment of the invention, the binder dispersion may bemixed with the synthetic microfibers prior to formation of the nonwovenweb via a wet-laid nonwoven process. Subsequent to the applying thebinder dispersion, the nonwoven article and the binder dispersion can besubjected to a drying step in order to allow the binder to set.Typically, the sulfopolyester binder can make up at least 1, 2, 3, 4, 5,or 7 weight percent of the nonwoven article and/or not more than 40, 30,20, 15, or 12 weight percent of the nonwoven article.

Undissolved or dried sulfopolyesters are known to form strong adhesivebonds to a wide array of substrates, including, but not limited to fluffpulp, cotton, acrylics, rayon, lyocell, PLA (polylactides), celluloseacetate, cellulose acetate propionate, poly(ethylene) terephthalate,poly(butylene) terephthalate, poly(trimethylene) terephthalate,poly(cyclohexylene) terephthalate, copolyesters, polyamides (e.g.,nylons), stainless steel, aluminum, treated polyolefins, PAN(polyacrylonitriles), and polycarbonates. Thus, sulfopolyesters functionas excellent binders for the nonwoven article. Therefore, our novelnonwoven articles may have multiple functionalities when asulfopolyester binder is utilized.

The nonwoven article may further comprise a coating. After the nonwovenarticle and the binder dispersion are subjected to drying, a coating maybe applied to the nonwoven article. The coating can comprise adecorative coating, a printing ink, a barrier coating, an adhesivecoating, and a heat seal coating. In another example, the coating cancomprise a liquid barrier and/or a microbial barrier.

After producing the nonwoven article, adding the binder, and/or afteradding the optional coating, the nonwoven article may undergo a heatsetting step comprising heating the nonwoven article to a temperature ofat least 100° C., and more preferably to at least about 120° C. The heatsetting step relaxes out internal fiber stresses and aids in producing adimensionally stable fabric product. It is preferred that when the heatset material is reheated to the temperature to which it was heatedduring the heat setting step that it exhibits surface area shrinkage ofless than about 10, 5, or 1 percent of its original surface area.However, if the nonwoven article is subjected to heat setting, then thenonwoven article cannot be repulpable and/or recycled by repulping thenonwoven article after use.

The term “repulpable,” as used herein, refers to any nonwoven articlethat has not been subjected to heat setting and is capable ofdisintegrating at 3,000 rpm at 1.2 percent consistency after 5,000,10,000, or 15,000 revolutions according to TAPPI standards.

In another aspect of the invention, the nonwoven article can furthercomprise at least one or more additional fibers. The additional fiberscan have a different composition and/or configuration (e.g., length,minimum transverse dimension, maximum transverse dimension,cross-sectional shape, or combinations thereof) than the syntheticmicrofibers. In one embodiment of the invention, the other fiber can beselected from the group comprising of thermoplastic polycondensatefibers, cellulosic fiber pulp, inorganic fibers (e.g., glass, carbon,boron, ceramic, and combinations thereof), polyester fibers, nylonfibers, polyolefin fibers, rayon fibers, lyocell fibers, cellulose esterfibers, post consumer recycled fibers, and combinations thereof. Thenonwoven article can comprise additional fibers in an amount of at least10, 15, 20, 25, 30, 40, or 60 weight percent of the nonwoven articleand/or not more than 95, 90, 85, 80, 70, 60, or 50 weight percent of thenonwoven article. In one embodiment, the additional fiber is acellulosic fiber that comprises at least 10, 25, or 40 weight percentand/or no more than 80, 70, 60, or 50 weight percent of the nonwovenarticle. The cellulosic fibers can comprise hardwood pulp fibers,softwood pulp fibers, and/or regenerated cellulose fibers. In anotherembodiment, at least one of the additional fibers is a glass fiber thathas a minimum transverse dimension of less than 30, 25, 10, 8, 6, 4, 2,or 1 microns.

In one embodiment, a combination of the synthetic microfibers, at leastone or more additional fibers, and the sulfopolyester binder make up atleast 75, 85, 95, or 98 weight percent of the nonwoven article.

The nonwoven article can further comprise one or more additives. Theadditives may be added to the wet lap of water non-dispersiblemicrofibers prior to subjecting the wet lap to a wet-laid or dry-laidprocess. The additives may also be added to the nonwoven article as acomponent of the binder or coating composition. Additives include, butare not limited to, starches, fillers, light and heat stabilizers,antistatic agents, extrusion aids, dyes, anticounterfeiting markers,slip agents, tougheners, adhesion promoters, oxidative stabilizers, UVabsorbers, colorants, pigments, opacifiers (delustrants), opticalbrighteners, fillers, nucleating agents, plasticizers, viscositymodifiers, surface modifiers, antimicrobials, antifoams, lubricants,thermostabilizers, emulsifiers, disinfectants, cold flow inhibitors,branching agents, oils, waxes, and catalysts. In one embodiment, the nonwoven web comprises an optical brightener and/or antimicrobials. Thenonwoven article can comprise at least 0.05, 0.1, or 0.5 weight percentand/or not more than 10, 5, or 2 weight percent of one or moreadditives.

In one embodiment of the invention, the short-cut microfibers used tomake the nonwoven article are ribbon fibers derived from amulticomponent fiber having a striped configuration. Such ribbon fiberscan exhibit a transverse aspect ratio of at least 2:1, 6:1, or 10:1and/or not more than 100:1, 50:1, or 20:1. As used herein, “transverseaspect ratio” denotes the ratio of a fiber's maximum transversedimension to the fiber's minimum transverse dimension. As used herein,“maximum transverse dimension” is the maximum dimension of a fibermeasured perpendicular to the axis of elongation of the fiber by theexternal caliper method described above.

Although it its known in the art that fibers having a transverse aspectratio of 1.5:1 or greater can be produced by fibrillation of a basemember (e.g., a sheet or a root fiber), the ribbon fibers provided inaccordance with one embodiment of the present invention are not made byfibrillating a sheet or root fiber to produce a “fuzzy” sheet or rootfiber having microfibers appended thereto. Rather, in one embodiment ofthe present invention, less than 50, 20, or 5 weight percent of ribbonfibers employed in the nonwoven article are joined to a base memberhaving the same composition as said ribbon fibers. In one embodiment,the ribbon fibers are derived from striped multi-component fibers havingsaid ribbon fibers as a component thereof.

When the nonwoven article of the present invention comprises short-cutribbon fibers, the major transverse axis of at least 50, 75, or 90weight percent of the ribbon microfibers in the nonwoven article can beoriented at an angle of less than 30, 20, 15, or 10 degrees from thenearest surface of the nonwoven article. As used herein, “majortransverse axis” denotes an axis perpendicular to the direction ofelongation of a fiber and extending through the centermost two points onthe outer surface of the fiber between which the maximum transversedimension of the fiber is measured by the external caliper methoddescribed above. Such orientation of the ribbon fibers in the nonwovenarticle can be facilitated by enhanced dilution of the fibers in awet-laid process and/or by mechanically pressing the nonwoven articleafter its formation. FIG. 2 illustrates how the angle of orientation ofthe ribbon fibers relative to the major transverse axis is determined.

Generally, manufacturing processes to produce nonwoven articles fromwater non-dispersible microfibers derived from multicomponent fibers canbe split into the following groups: dry-laid webs, wet-laid webs, andcombinations of these processes with each other or other nonwovenprocesses.

Generally, dry-laid nonwoven articles are made with staple fiberprocessing machinery that is designed to manipulate fibers in a drystate. These include mechanical processes, such as carding, aerodynamic,and other air-laid routes. Also included in this category are nonwovenarticles made from filaments in the form of tow, fabrics composed ofstaple fibers, and stitching filaments or yards (i.e., stitchbondednonwovens). Carding is the process of disentangling, cleaning, andintermixing fibers to make a web for further processing into a nonwovenarticle. The process predominantly aligns the fibers which are heldtogether as a web by mechanical entanglement and fiber-fiber friction.Cards (e.g., a roller card) are generally configured with one or moremain cylinders, roller or stationary tops, one or more doffers, orvarious combinations of these principal components. The carding actionis the combing or working of the water non-dispersible microfibersbetween the points of the card on a series of interworking card rollers.Types of cards include roller, woolen, cotton, and random cards.Garnetts can also be used to align these fibers.

The water non-dispersible microfibers in the dry-laid process can alsobe aligned by air-laying. These fibers are directed by air current ontoa collector which can be a flat conveyor or a drum.

Wet laid processes involve the use of papermaking technology to producenonwoven articles. These nonwoven articles are made with machineryassociated with pulp fiberizing (e.g., hammer mills) and paperforming(e.g., slurry pumping onto continuous screens which are designed tomanipulate short fibers in a fluid).

In one embodiment of the wet laid process, water non-dispersiblemicrofibers are suspended in water, brought to a forming unit whereinthe water is drained off through a forming screen, and the fibers aredeposited on the screen wire.

In another embodiment of the wet laid process, water non-dispersiblemicrofibers are dewatered on a sieve or a wire mesh which revolves athigh speeds of up to 1,500 meters per minute at the beginning ofhydraulic formers over dewatering modules (e.g., suction boxes, foils,and curatures). The sheet is dewatered to a solid content ofapproximately 20 to 30 percent. The sheet can then be pressed and dried.

In another embodiment of the wet-laid process, a process is providedcomprising:

(a) optionally, rinsing the water non-dispersible microfibers withwater;

(b) adding water to the water non-dispersible microfibers to produce awater non-dispersible microfiber slurry;

(c) optionally, adding other fibers and/or additives to the waternon-dispersible microfiber slurry; and

(d) transferring the water non-dispersible microfiber slurry to awet-laid nonwoven zone to produce the nonwoven article.

In step (a), the number of rinses depends on the particular use chosenfor the water non-dispersible microfibers. In step (b), sufficient wateris added to the microfibers to allow them to be routed to the wet-laidnonwoven zone.

The wet-laid nonwoven zone in step (d) comprises any equipment known inthe art that can produce wet-laid nonwoven articles. In one embodimentof the invention, the wet-laid nonwoven zone comprises at least onescreen, mesh, or sieve in order to remove the water from the waternon-dispersible microfiber slurry.

In another embodiment of the invention, the water non-dispersiblemicrofiber slurry is mixed prior to transferring to the wet-laidnonwoven zone.

The nonwoven articles also may comprise one or more layers ofwater-dispersible fibers, multicomponent fibers, or microdenier fibers.

The nonwoven articles may also include various powders and particulatesto improve the absorbency nonwoven article and its ability to functionas a delivery vehicle for other additives. Examples of powders andparticulates include, but are not limited to, talc, starches, variouswater absorbent, water-dispersible, or water swellable polymers (e.g.,super absorbent polymers, sulfopolyesters, and poly(vinylalcohols)),silica, activated carbon, pigments, and microcapsules. As previouslymentioned, additives may also be present, but are not required, asneeded for specific applications. Examples of additives include, but arenot limited to, fillers, light and heat stabilizers, antistatic agents,extrusion aids, dyes, anticounterfeiting markers, slip agents,tougheners, adhesion promoters, oxidative stabilizers, UV absorbers,colorants, pigments, opacifiers (delustrants), optical brighteners,fillers, nucleating agents, plasticizers, viscosity modifiers, surfacemodifiers, antimicrobials, antifoams, lubricants, thermostabilizers,emulsifiers, disinfectants, cold flow inhibitors, branching agents,oils, waxes, and catalysts.

The nonwoven article may further comprise a water-dispersible filmcomprising at least one second water-dispersible polymer. The secondwater-dispersible polymer may be the same as or different from thepreviously described water-dispersible polymers used in the fibers andnonwoven articles of the present invention. In one embodiment, forexample, the second water-dispersible polymer may be an additionalsulfopolyester which, in turn, can comprise:

(a) at least 50, 60, 70, 75, 85, or 90 mole percent and no more than 95mole percent of one or more residues of isophthalic acid or terephthalicacid, based on the total acid residues;

(b) at least 4 to about 30 mole percent, based on the total acidresidues, of a residue of sodiosulfoisophthalic acid;

(c) one or more diol residues, wherein at least 15, 25, 50, 70, or 75mole percent and no more than 95 mole percent, based on the total diolresidues, is a poly(ethylene glycol) having a structureH—(OCH₂—CH₂)_(n)—OH wherein n is an integer in the range of 2 to about500;

(d) 0 to about 20 mole percent, based on the total repeating units, ofresidues of a branching monomer having three or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof.

The additional sulfopolyester may be blended with one or moresupplemental polymers, as described hereinabove, to modify theproperties of the resulting nonwoven article. The supplemental polymermay or may not be water-dispersible depending on the application. Thesupplemental polymer may be miscible or immiscible with the additionalsulfopolyester.

The additional sulfopolyester also may include the residues of ethyleneglycol and/or 1,4-cyclohexanedimethanol. The additional sulfopolyestermay further comprise at least 10, 20, 30, or 40 mole percent and/or nomore than 75, 65, or 60 mole percent CHDM. The additional sulfopolyestermay further comprise ethylene glycol residues in the amount of at least10, 20, 25, or 40 mole percent and no more than 75, 65, or 60 molepercent ethylene glycol residues. In one embodiment, the additionalsulfopolyester comprises is at about 75 to about 96 mole percent of theresidues of isophthalic acid and about 25 to about 95 mole percent ofthe residues of diethylene glycol.

According to the invention, the sulfopolyester film component of thenonwoven article may be produced as a monolayer or multilayer film. Themonolayer film may be produced by conventional casting techniques. Themultilayered films may be produced by conventional lamination methods orthe like. The film may be of any convenient thickness, but totalthickness will normally be between about 2 and about millimeters.

A major advantage inherent to the water dispersible sulfopolyesters ofthe present invention relative to the caustic-dissipatable polymers(including sulfopolyesters) known in the art is the facile ability toremove or recover the polymer from aqueous dispersions via flocculationand precipitation by adding ionic moieties (i.e., salts). pH adjustment,adding nonsolvents, freezing, membrane filtration and so forth may alsobe employed. The recovered water dispersible sulfopolyester may find usein applications, including, but not limited to, the aforementionedsulfopolyester binder for wet-laid nonwovens comprising the syntheticmicrofibers of the invention.

The present invention provides a microfiber-generating multicomponentfiber that includes at least two components, at least one of which is awater-dispersible sulfopolyester and at least one of which is a waternon-dispersible synthetic polymer. As is discussed below in furtherdetail, the water-dispersible component can comprise a sulfopolyesterfiber and the water non-dispersible component can comprise a waternon-dispersible synthetic polymer.

The term “multicomponent fiber” as used herein, is intended to mean afiber prepared by melting at least two or more fiber-forming polymers inseparate extruders, directing the resulting multiple polymer flows intoone spinneret with a plurality of distribution flow paths, and spinningthe flow paths together to form one fiber. Multicomponent fibers arealso sometimes referred to as conjugate or bicomponent fibers. Thepolymers are arranged in distinct segments or configurations across thecross-section of the multicomponent fibers and extend continuously alongthe length of the multicomponent fibers. The configurations of suchmulticomponent fibers may include, for example, sheath core, side byside, segmented pie, striped, or islands-in-the-sea. For example, amulticomponent fiber may be prepared by extruding the sulfopolyester andone or more water non-dispersible synthetic polymers separately througha spinneret having a shaped or engineered transverse geometry such as,for example, an “islands-in-the-sea,” striped, or segmented pieconfiguration.

Additional disclosures regarding multicomponent fibers, how to producethem, and their use to generate microfibers are disclosed in U.S. Pat.No. 6,989,193, US Patent Application Publication No. 2005/0282008, USPatent Application Publication No. 2006/0194047, U.S. Pat. No.7,687,143, US Patent Application No. 2008/0311815, and US PatentApplication Publication No. 2008/0160859, the disclosures of which areincorporated herein by reference.

The terms “segment,” and/or “domain,” when used to describe the shapedcross section of a multicomponent fiber refer to the area within thecross section comprising the water non-dispersible synthetic polymers.These domains or segments are substantially isolated from each other bythe water-dispersible sulfopolyester, which intervenes between thesegments or domains. The term “substantially isolated,” as used herein,is intended to mean that the segments or domains are set apart from eachother to permit the segments or domains to form individual fibers uponremoval of the sulfopolyester. Segments or domains can be of similarshape and size or can vary in shape and/or size. Furthermore, thesegments or domains can be “substantially continuous” along the lengthof the multicomponent fiber. The term “substantially continuous” meansthat the segments or domains are continuous along at least 10 cm lengthof the multicomponent fiber. These segments or domains of themulticomponent fiber produce the water non-dispersible microfibers whenthe water dispersible sulfopolyester is removed.

The term “water-dispersible,” as used in reference to thewater-dispersible component and the sulfopolyesters is intended to besynonymous with the terms “water-dissipatable,” “water-disintegratable,”“water-dissolvable,” “water-dispellable,” “water soluble,”“water-removable,” “hydrosoluble,” and “hydrodispersible” and isintended to mean that the sulfopolyester component is sufficientlyremoved from the multicomponent fiber and is dispersed and/or dissolvedby the action of water to enable the release and separation of the waternon-dispersible fibers contained therein. The terms “dispersed,”“dispersible,” “dissipate,” or “dissipatable” mean that, when using asufficient amount of deionized water (e.g., 100:1 water:fiber by weight)to form a loose suspension or slurry of the sulfopolyester fibers at atemperature of about 60° C., and within a time period of up to 5 days,the sulfopolyester component dissolves, disintegrates, or separates fromthe multicomponent fiber, thus leaving behind a plurality of microfibersfrom the water non-dispersible segments.

In the context of this invention, all of these terms refer to theactivity of water or a mixture of water and a water-miscible cosolventon the sulfopolyesters described herein. Examples of such water-misciblecosolvents includes alcohols, ketones, glycol ethers, esters and thelike. It is intended for this terminology to include conditions wherethe sulfopolyester is dissolved to form a true solution as well as thosewhere the sulfopolyester is dispersed within the aqueous medium. Often,due to the statistical nature of sulfopolyester compositions, it ispossible to have a soluble fraction and a dispersed fraction when asingle sulfopolyester sample is placed in an aqueous medium.

The term “polyester”, as used herein, encompasses both “homopolyesters”and “copolyesters” and means a synthetic polymer prepared by thepolycondensation of difunctional carboxylic acids with a difunctionalhydroxyl compound. Typically, the difunctional carboxylic acid is adicarboxylic acid and the difunctional hydroxyl compound is a dihydricalcohol such as, for example, glycols and diols. Alternatively, thedifunctional carboxylic acid may be a hydroxy carboxylic acid such as,for example, p-hydroxybenzoic acid, and the difunctional hydroxylcompound may be an aromatic nucleus bearing two hydroxy substituentssuch as, for example, hydroquinone. As used herein, the term“sulfopolyester” means any polyester comprising a sulfomonomer. The term“residue,” as used herein, means any organic structure incorporated intoa polymer through a polycondensation reaction involving thecorresponding monomer. Thus, the dicarboxylic acid residue may bederived from a dicarboxylic acid monomer or its associated acid halides,esters, salts, anhydrides, or mixtures thereof. Therefore, the termdicarboxylic acid is intended to include dicarboxylic acids and anyderivative of a dicarboxylic acid, including its associated acidhalides, esters, half-esters, salts, half-salts, anhydrides, mixedanhydrides, or mixtures thereof, useful in a polycondensation processwith a diol to make high molecular weight polyesters.

The water-dispersible sulfopolyesters generally comprise dicarboxylicacid monomer residues, sulfomonomer residues, diol monomer residues, andrepeating units. The sulfomonomer may be a dicarboxylic acid, a diol, orhydroxycarboxylic acid. The term “monomer residue,” as used herein,means a residue of a dicarboxylic acid, a diol, or a hydroxycarboxylicacid. A “repeating unit,” as used herein, means an organic structurehaving 2 monomer residues bonded through a carbonyloxy group. Thesulfopolyesters of the present invention contain substantially equalmolar proportions of acid residues (100 mole percent) and diol residues(100 mole percent), which react in substantially equal proportions suchthat the total moles of repeating units is equal to 100 mole percent.The mole percentages provided in the present disclosure, therefore, maybe based on the total moles of acid residues, the total moles of diolresidues, or the total moles of repeating units. For example, asulfopolyester containing 30 mole percent of a sulfomonomer, which maybe a dicarboxylic acid, a diol, or hydroxycarboxylic acid, based on thetotal repeating units, means that the sulfopolyester contains 30 molepercent sulfomonomer out of a total of 100 mole percent repeating units.Thus, there are 30 moles of sulfomonomer residues among every 100 molesof repeating units. Similarly, a sulfopolyester containing 30 molepercent of a sulfonated dicarboxylic acid, based on the total acidresidues, means the sulfopolyester contains 30 mole percent sulfonateddicarboxlyic acid out of a total of 100 mole percent acid residues.Thus, in this latter case, there are 30 moles of sulfonated dicarboxylicacid residues among every 100 moles of acid residues.

In addition, our invention also provides a process for producing themulticomponent fibers and the microfibers derived therefrom, the processcomprising (a) producing the multicomponent fiber and (b) generating themicrofibers from the multicomponent fibers.

The process begins by (a) spinning a water dispersible sulfopolyesterhaving a glass transition temperature (Tg) of at least 36° C., 40° C.,or 57° C. and one or more water non-dispersible synthetic polymersimmiscible with the sulfopolyester into multicomponent fibers. Themulticomponent fibers can have a plurality of segments comprising thewater non-dispersible synthetic polymers that are substantially isolatedfrom each other by the sulfopolyester, which intervenes between thesegments. The sulfopolyester comprises:

(i) about 50 to about 96 mole percent of one or more residues ofisophthalic acid and/or terephthalic acid, based on the total acidresidues;

(ii) about 4 to about 30 mole percent, based on the total acid residues,of a residue of sodiosulfoisophthalic acid;

(iii) one or more diol residues, wherein at least 25 mole percent, basedon the total diol residues, is a poly(ethylene glycol) having astructure H—(OCH₂—CH₂)_(n)—OH wherein n is an integer in the range of 2to about 500; and

(iv) 0 to about 20 mole percent, based on the total repeating units, ofresidues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof. Ideally, the sulfopolyester has a melt viscosity of less than12,000, 8,000, or 6,000 poise measured at 240° C. at a strain rate of 1rad/sec.

The microfibers are generated by (b) contacting the multicomponentfibers with water to remove the sulfopolyester thereby forming themicrofibers comprising the water non-dispersible synthetic polymer. Thewater non-dispersible microfibers of the instant invention can have anaverage fineness of at least 0.001, 0.005, or 0.01 dpf and/or no morethan 0.1 or 0.5 dpf. Typically, the multicomponent fiber is contactedwith water at a temperature of about 25° C. to about 100° C., preferablyabout 50° C. to about 80° C., for a time period of from about 10 toabout 600 seconds whereby the sulfopolyester is dissipated or dissolved.

The ratio by weight of the sulfopolyester to water non-dispersiblesynthetic polymer component in the multicomponent fiber of the inventionis generally in the range of about 98:2 to about 2:98 or, in anotherexample, in the range of about 25:75 to about 75:25. Typically, thesulfopolyester comprises 50 percent by weight or less of the totalweight of the multicomponent fiber.

The shaped cross section of the multicomponent fibers can be, forexample, in the form of a sheath core, islands-in-the-sea, segmentedpie, hollow segmented pie, off-centered segmented pie, or striped.

For example, the striped configuration can have alternating waterdispersible segments and water non-dispersible segments and have atleast 4, 8, or 12 stripes and/or less than 50, 35, or 20 stripes.

The multicomponent fibers of the present invention can be prepared in anumber of ways. For example, in U.S. Pat. No. 5,916,678, multicomponentfibers may be prepared by extruding the sulfopolyester and one or morewater non-dispersible synthetic polymers, which are immiscible with thesulfopolyester, separately through a spinneret having a shaped orengineered transverse geometry such as, for example, islands-in-the-sea,sheath core, side-by-side, striped, or segmented pie. The sulfopolyestermay be later removed by dissolving the interfacial layers or piesegments and leaving the microdenier fibers of the water non-dispersiblesynthetic polymer(s). These microdenier fibers of the waternon-dispersible synthetic polymer(s) have fiber sizes much smaller thanthe multicomponent fiber. Another example includes feeding thesulfopolyester and water non-dispersible synthetic polymers to a polymerdistribution system where the polymers are introduced into a segmentedspinneret plate. The polymers follow separate paths to the fiberspinneret and are combined at the spinneret hole. The spinneret holecomprises either two concentric circular holes, thus providing a sheathcore type fiber, or a circular spinneret hole divided along a diameterinto multiple parts to provide a fiber having a side-by-side type.Alternatively, the sulfopolyester and water non-dispersible syntheticpolymers may be introduced separately into a spinneret having aplurality of radial channels to produce a multicomponent fiber having asegmented pie cross section. Typically, the sulfopolyester will form the“sheath” component of a sheath core configuration. Another alternativeprocess involves forming the multicomponent fibers by melting thesulfopolyester and water non-dispersible synthetic polymers in separateextruders and directing the polymer flows into one spinneret with aplurality of distribution flow paths in form of small thin tubes orsegments to provide a fiber having an islands-in-the-sea shaped crosssection. An example of such a spinneret is described in U.S. Pat. No.5,366,804. In the present invention, typically, the sulfopolyester willform the “sea” component and the water non-dispersible synthetic polymerwill form the “islands” component.

As some water-dispersible sulfopolyesters are generally resistant toremoval during subsequent hydroentangling processes, it is preferablethat the water used to remove the sulfopolyester from the multicomponentfibers be above room temperature, more preferably the water is at leastabout 45° C., 60° C., or 85° C.

In another embodiment of this invention, another process is provided toproduce water non-dispersible microfibers. The process comprises:

(a) cutting a multicomponent fiber into cut multicomponent fibers havinga length of less than 25 millimeters;

(b) contacting a fiber-containing feedstock comprising the cutmulticomponent fibers with a wash water for at least 0.1, 0.5, or 1minutes and/or not more than 30, 20, or 10 minutes to produce a fibermix slurry, wherein the wash water can have a pH of less than 10, 8,7.5, or 7 and can be substantially free of added caustic;

(c) heating said fiber mix slurry to produce a heated fiber mix slurry;

(d) optionally, mixing said fiber mix slurry in a shearing zone;

(e) removing at least a portion of the sulfopolyester from themulticomponent fiber to produce a slurry mixture comprising asulfopolyester dispersion and the water non-dispersible microfibers;

(f) removing at least a portion of the sulfopolyester dispersion fromthe slurry mixture to thereby provide a wet lap comprising the waternon-dispersible microfibers, wherein the wet lap is comprised of atleast 5, 10, 15, or 20 weight percent and/or not more than 70, 55, or 40weight percent of the water non-dispersible microfiber and at least 30,45, or 60 weight percent and/or not more than 90, 85, or 80 weightpercent of the sulfopolyester dispersion; and

(g) optionally, combining the wet lap with a dilution liquid to producea dilute wet-lay slurry comprising the water non-dispersible microfibersin an amount of at least 0.0001, 0.001, or 0.005 weight percent and/ornot more than 1, 0.5, or 0.1 weight percent.

In another embodiment, the wet lap is comprised of at least 5, 10, 15,or 20 weight percent and/or not more than 50, 45, or 40 weight percentof the water non-dispersible microfiber and at least 50, 55, or 60weight percent and/or not more than 90, 85, or 80 weight percent of thesulfopolyester dispersion.

The multicomponent fiber can be cut into any length that can be utilizedto produce nonwoven articles. In one embodiment of the invention, themulticomponent fiber is cut into lengths ranging of at least 0.1, 0.25,or 0.5 millimeter and/or not more than 25, 10, 5, or 2 millimeter. Inone embodiment, the cutting ensures a consistent fiber length so that atleast 75, 85, 90, 95, or 98 percent of the individual fibers have anindividual length that is within 90, 95, or 98 percent of the averagelength of all fibers.

The fiber-containing feedstock can comprise any other type of fiber thatis useful in the production of nonwoven articles. In one embodiment, thefiber-containing feedstock further comprises at least one fiber selectedfrom the group consisting of cellulosic fiber pulp, inorganic fibersincluding glass, carbon, boron and ceramic fibers, polyester fibers,lyocell fibers, nylon fibers, polyolefin fibers, rayon fibers, andcellulose ester fibers.

The fiber-containing feedstock is mixed with a wash water to produce afiber mix slurry. Preferably, to facilitate the removal of thewater-dispersible sulfopolyester, the water utilized can be soft wateror deionized water. The wash water can have a pH of less than 10, 8,7.5, or 7 and can be substantially free of added caustic. The wash watercan be maintained at a temperature of at least 140° F., 150° F., or 160°F. and/or not more than 210° F., 200° F., or 190° F. during contactingof step (b). In one embodiment, the wash water contacting of step (b)can disperse substantially all of the water-dispersible sulfopolyestersegments of the multicomponent fiber, so that the dissociated waternon-dispersible microfibers have less than 5, 2, or 1 weight percent ofresidual water dispersible sulfopolyester disposed thereon.

The fiber mix slurry can be heated to facilitate removal of the waterdispersible sulfopolyester. In one embodiment of the invention, thefiber mix slurry is heated to at least 50° C., 60° C., 70° C., 80° C. or90° C. and no more than 100° C.

Optionally, the fiber mix slurry can be mixed in a shearing zone. Theamount of mixing is that which is sufficient to disperse and remove aportion of the water dispersible sulfopolyester from the multicomponentfiber. During mixing, at least 90, 95, or 98 weight percent of thesulfopolyester can be removed from the water non-dispersible microfiber.The shearing zone can comprise any type of equipment that can provide aturbulent fluid flow necessary to disperse and remove a portion of thewater dispersible sulfopolyester from the multicomponent fiber andseparate the water non-dispersible microfibers. Examples of suchequipment include, but is not limited to, pulpers and refiners.

After contacting the multicomponent fiber with water, the waterdispersible sulfopolyester dissociates with the water non-dispersiblesynthetic polymer fiber to produce a slurry mixture comprising asulfopolyester dispersion and the water non-dispersible microfibers. Thesulfopolyester dispersion can be separated from the waternon-dispersible microfibers by any means known in the art in order toproduce a wet lap, wherein the sulfopolyester dispersion and the waternon-dispersible microfibers in combination can make up at least 95, 98,or 99 weight percent of the wet lap. For example, the slurry mixture canbe routed through separating equipment such as, for example, screens andfilters. Optionally, the water non-dispersible microfibers may be washedonce or numerous times to remove more of the water dispersiblesulfopolyester.

The wet lap can comprise up to at least 30, 45, 50, 55, or 60 weightpercent and/or not more than 90, 86, 85, or 80 weight percent water.Even after removing some of the sulfopolyester dispersion, the wet lapcan comprise at least 0.001, 0.01, or 0.1 and/or not more than 10, 5, 2,or 1 weight percent of water dispersible sulfopolyesters. In addition,the wet lap can further comprise a fiber finishing compositioncomprising an oil, a wax, and/or a fatty acid. The fatty acid and/or oilused for the fiber finishing composition can be naturally-derived. Inanother embodiment, the fiber finishing composition comprises mineraloil, stearate esters, sorbitan esters, and/or neatsfoot oil. The fiberfinishing composition can make up at least 10, 50, or 100 ppmw and/ornot more than 5,000, 1000, or 500 ppmw of the wet lap.

The removal of the water-dispersible sulfopolyester can be determined byphysical observation of the slurry mixture. The water utilized to rinsethe water non-dispersible microfibers is clear if the water-dispersiblesulfopolyester has been mostly removed. If the water dispersiblesulfopolyester is still present in noticeable amounts, then the waterutilized to rinse the water non-dispersible microfibers can be milky incolor. Further, if water-dispersible sulfopolyester remains on the waternon-dispersible microfibers, the microfibers can be somewhat sticky tothe touch.

The dilute wet-lay slurry of step (g) can comprise the dilution liquidin an amount of at least 90, 95, 98, 99, or 99.9 weight percent. In oneembodiment, an additional fiber can be combined with the wet lap anddilution liquid to produce the dilute wet-lay slurry. The additionalfibers can have a different composition and/or configuration than thewater non-dispersible microfiber and can be any that is known in the artdepending on the type of nonwoven article to be produced. In oneembodiment of the invention, the other fiber can be selected from thegroup consisting cellulosic fiber pulp, inorganic fibers (e.g., glass,carbon, boron, ceramic, and combinations thereof), polyester fibers,nylon fibers, polyolefin fibers, rayon fibers, lyocell fibers, celluloseester fibers, and combinations thereof. The dilute wet-lay slurry cancomprise additional fibers in an amount of at least 0.001, 0.005, or0.01 weight percent and/or not more than 1, 0.5, or 0.1 weight percent.

In one embodiment of this invention, at least one water softening agentmay be used to facilitate the removal of the water-dispersiblesulfopolyester from the multicomponent fiber. Any water softening agentknown in the art can be utilized. In one embodiment, the water softeningagent is a chelating agent or calcium ion sequestrant. Applicablechelating agents or calcium ion sequestrants are compounds containing aplurality of carboxylic acid groups per molecule where the carboxylicgroups in the molecular structure of the chelating agent are separatedby 2 to 6 atoms. Tetrasodium ethylene diamine tetraacetic acid (EDTA) isan example of the most common chelating agent, containing fourcarboxylic acid moieties per molecular structure with a separation of 3atoms between adjacent carboxylic acid groups. Sodium salts of maleicacid or succinic acid are examples of the most basic chelating agentcompounds. Further examples of applicable chelating agents includecompounds which have multiple carboxylic acid groups in the molecularstructure wherein the carboxylic acid groups are separated by therequired distance (2 to 6 atom units) which yield a favorable stericinteraction with di- or multi-valent cations such as calcium which causethe chelating agent to preferentially bind to di- or multi valentcations. Such compounds include, for example,diethylenetriaminepentaacetic acid;diethylenetriamine-N,N,N′,N′,N″-pentaacetic acid; pentetic acid;N,N-bis(2-(bis-(carboxymethyl)amino)ethyl)-glycine; diethylenetriaminepentaacetic acid;[[(carboxymethyl)imino]bis(ethylenenitrilo)]-tetra-acetic acid; edeticacid; ethylenedinitrilotetraacetic acid; EDTA, free base; EDTA, freeacid; ethylenediamine-N,N,N′,N′-tetraacetic acid; hampene; versene;N,N′-1,2-ethane diylbis-(N-(carboxymethyl)glycine); ethylenediaminetetra-acetic acid; N,N-bis(carboxymethyl)glycine; triglycollamic acid;trilone A; α,α′,α″-5 trimethylaminetricarboxylic acid;tri(carboxymethyl)amine; aminotriacetic acid; hampshire NTA acid;nitrilo-2,2′,2″-triacetic acid; titriplex i; nitrilotriacetic acid; andmixtures thereof.

The water dispersible sulfopolyester can be recovered from thesulfopolyester dispersion by any method known in the art.

The sulfopolyesters described herein can have an inherent viscosity,abbreviated hereinafter as “I.V.”, of at least about 0.1, 0.2, or 0.3dL/g, preferably about 0.2 to 0.3 dL/g, and most preferably greater thanabout 0.3 dL/g, as measured in 60/40 parts by weight solution ofphenol/tetrachloroethane solvent at 25° C. and at a concentration ofabout 0.5 g of sulfopolyester in 100 mL of solvent.

The sulfopolyesters of the present invention can include one or moredicarboxylic acid residues. Depending on the type and concentration ofthe sulfomonomer, the dicarboxylic acid residue may comprise at least60, 65, or 70 mole percent and no more than 95 or 100 mole percent ofthe acid residues. Examples of dicarboxylic acids that may be usedinclude aliphatic dicarboxylic acids, alicyclic dicarboxylic acids,aromatic dicarboxylic acids, or mixtures of two or more of these acids.Thus, suitable dicarboxylic acids include, but are not limited to,succinic, glutaric, adipic, azelaic, sebacic, fumaric, maleic, itaconic,1,3-cyclohexanedicarboxylic, 1,4cyclohexanedicarboxylic, diglycolic,2,5-norbornanedicarboxylic, phthalic, terephthalic,1,4-naphthalenedicarboxylic, 2,5-naphthalenedicarboxylic, diphenic,4,4′-oxydibenzoic, 4,4′-sulfonyldibenzoic, and isophthalic. Thepreferred dicarboxylic acid residues are isophthalic, terephthalic, and1,4-cyclohexanedicarboxylic acids, or if diesters are used, dimethylterephthalate, dimethyl isophthalate, anddimethyl-1,4-cyclohexanedicarboxylate with the residues of isophthalicand terephthalic acid being especially preferred. Although thedicarboxylic acid methyl ester is the most preferred embodiment, it isalso acceptable to include higher order alkyl esters, such as ethyl,propyl, isopropyl, butyl, and so forth. In addition, aromatic esters,particularly phenyl, also may be employed.

The sulfopolyesters can include at least 4, 6, or 8 mole percent and nomore than about 40, 35, 30, or 25 mole percent, based on the totalrepeating units, of residues of at least one sulfomonomer having 2functional groups and one or more sulfonate groups attached to anaromatic or cycloaliphatic ring wherein the functional groups arehydroxyl, carboxyl, or a combination thereof. The sulfomonomer may be adicarboxylic acid or ester thereof containing a sulfonate group, a diolcontaining a sulfonate group, or a hydroxy acid containing a sulfonategroup. The term “sulfonate” refers to a salt of a sulfonic acid havingthe structure “—SO₃M,” wherein M is the cation of the sulfonate salt.The cation of the sulfonate salt may be a metal ion such as Li⁺, Na⁺,K⁺, and the like.

When a monovalent alkali metal ion is used as the cation of thesulfonate salt, the resulting sulfopolyester is completely dispersiblein water with the rate of dispersion dependent on the content ofsulfomonomer in the polymer, temperature of the water, surfacearea/thickness of the sulfopolyester, and so forth. When a divalentmetal ion is used, the resulting sulfopolyesters are not readilydispersed by cold water but are more easily dispersed by hot water.Utilization of more than one counterion within a single polymercomposition is possible and may offer a means to tailor or fine-tune thewater-responsivity of the resulting article of manufacture. Examples ofsulfomonomers residues include monomer residues where the sulfonate saltgroup is attached to an aromatic acid nucleus, such as, for example,benzene, naphthalene, diphenyl, oxydiphenyl, sulfonyldiphenyl,methylenediphenyl, or cycloaliphatic rings (e.g., cyclopentyl,cyclobutyl, cycloheptyl, and cyclooctyl). Other examples of sulfomonomerresidues which may be used in the present invention are the metalsulfonate salts of sulfophthalic acid, sulfoterephthalic acid,sulfoisophthalic acid, or combinations thereof. Other examples ofsulfomonomers which may be used include 5-sodiosulfoisophthalic acid andesters thereof.

The sulfomonomers used in the preparation of the sulfopolyesters areknown compounds and may be prepared using methods well known in the art.For example, sulfomonomers in which the sulfonate group is attached toan aromatic ring may be prepared by sulfonating the aromatic compoundwith oleum to obtain the corresponding sulfonic acid and followed byreaction with a metal oxide or base, for example, sodium acetate, toprepare the sulfonate salt. Procedures for preparation of varioussulfomonomers are described, for example, in U.S. Pat. No. 3,779,993;U.S. Pat. No. 3,018,272; and U.S. Pat. No. 3,528,947, the disclosures ofwhich are incorporated herein by reference.

The sulfopolyesters can include one or more diol residues which mayinclude aliphatic, cycloaliphatic, and aralkyl glycols. Thecycloaliphatic diols, for example, 1,3- and 1,4-cyclohexanedimethanol,may be present as their pure cis or trans isomers or as a mixture of cisand trans isomers. As used herein, the term “diol” is synonymous withthe term “glycol” and can encompass any dihydric alcohol. Examples ofdiols include, but are not limited to, ethylene glycol, diethyleneglycol, triethylene glycol, polyethylene glycols, 1,3-propanediol,2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol,2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol,p-xylylenediol, or combinations of one or more of these glycols.

The diol residues may include from about 25 mole percent to about 100mole percent, based on the total diol residues, of residues of apoly(ethylene glycol) having a structure H—(OCH₂—CH₂)_(n)—OH, wherein nis an integer in the range of 2 to about 500. Non-limiting examples oflower molecular weight polyethylene glycols (e.g., wherein n is from 2to 6) are diethylene glycol, triethylene glycol, and tetraethyleneglycol. Of these lower molecular weight glycols, diethylene andtriethylene glycol are most preferred. Higher molecular weightpolyethylene glycols (abbreviated herein as “PEG”), wherein n is from 7to about 500, include the commercially available products known underthe designation CARBOWAX®, a product of Dow Chemical Company (formerlyUnion Carbide). Typically, PEGs are used in combination with other diolssuch as, for example, diethylene glycol or ethylene glycol. Based on thevalues of n, which range from greater than 6 to 500, the molecularweight may range from greater than 300 to about 22,000 g/mol. Themolecular weight and the mole percent are inversely proportional to eachother; specifically, as the molecular weight is increased, the molepercent will be decreased in order to achieve a designated degree ofhydrophilicity. For example, it is illustrative of this concept toconsider that a PEG having a molecular weight of 1,000 g/mol mayconstitute up to 10 mole percent of the total diol, while a PEG having amolecular weight of 10,000 g/mol would typically be incorporated at alevel of less than 1 mole percent of the total diol.

Certain dimer, trimer, and tetramer diols may be formed in situ due toside reactions that may be controlled by varying the process conditions.For example, varying amounts of diethylene, triethylene, andtetraethylene glycols may be derived from ethylene glycol using anacid-catalyzed dehydration reaction which occurs readily when thepolycondensation reaction is carried out under acidic conditions. Thepresence of buffer solutions, well known to those skilled in the art,may be added to the reaction mixture to retard these side reactions.Additional compositional latitude is possible, however, if the buffer isomitted and the dimerization, trimerization, and tetramerizationreactions are allowed to proceed.

The sulfopolyesters of the present invention may include from 0 to lessthan 25, 20, 15, or 10 mole percent, based on the total repeating units,of residues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof. Non-limiting examples of branching monomers are1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin,pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol,trimellitic anhydride, pyromellitic dianhydride, dimethylol propionicacid, or combinations thereof. The presence of a branching monomer mayresult in a number of possible benefits to the sulfopolyesters,including but not limited to, the ability to tailor rheological,solubility, and tensile properties. For example, at a constant molecularweight, a branched sulfopolyester, compared to a linear analog, willalso have a greater concentration of end groups that may facilitatepost-polymerization crosslinking reactions. At high concentrations ofbranching agent, however, the sulfopolyester may be prone to gelation.

The sulfopolyester used for the multicomponent fiber can have a glasstransition temperature, abbreviated herein as “Tg,” of at least 25° C.,30° C., 36° C., 40° C., 45° C., 50° C., 55° C., 57° C., 60° C., or 65°C. as measured on the dry polymer using standard techniques well knownto persons skilled in the art, such as differential scanning calorimetry(“DSC”). The Tg measurements of the sulfopolyesters are conducted usinga “dry polymer,” that is, a polymer sample in which adventitious orabsorbed water is driven off by heating the polymer to a temperature ofabout 200° C. and allowing the sample to return to room temperature.Typically, the sulfopolyester is dried in the DSC apparatus byconducting a first thermal scan in which the sample is heated to atemperature above the water vaporization temperature, holding the sampleat that temperature until the vaporization of the water absorbed in thepolymer is complete (as indicated by a large, broad endotherm), coolingthe sample to room temperature, and then conducting a second thermalscan to obtain the Tg measurement.

In one embodiment, our invention provides a sulfopolyester having aglass transition temperature (Tg) of at least 25° C., wherein thesulfopolyester comprises:

(a) at least 50, 60, 75, or 85 mole percent and no more than 96, 95, 90,or 85 mole percent of one or more residues of isophthalic acid and/orterephthalic acid, based on the total acid residues;

(b) about 4 to about 30 mole percent, based on the total acid residues,of a residue of sodiosulfoisophthalic acid;

(c) one or more diol residues wherein at least 25, 50, 70, or 75 molepercent, based on the total diol residues, is a poly(ethylene glycol)having a structure H—(OCH₂—CH₂)_(n)—OH wherein n is an integer in therange of 2 to about 500;

(d) 0 to about 20 mole percent, based on the total repeating units, ofresidues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof.

The sulfopolyesters of the instant invention are readily prepared fromthe appropriate dicarboxylic acids, esters, anhydrides, salts,sulfomonomer, and the appropriate diol or diol mixtures using typicalpolycondensation reaction conditions. They may be made by continuous,semi-continuous, and batch modes of operation and may utilize a varietyof reactor types. Examples of suitable reactor types include, but arenot limited to, stirred tank, continuous stirred tank, slurry, tubular,wiped-film, falling film, or extrusion reactors. The term “continuous”as used herein means a process wherein reactants are introduced andproducts withdrawn simultaneously in an uninterrupted manner. By“continuous” it is meant that the process is substantially or completelycontinuous in operation and is to be contrasted with a “batch” process.“Continuous” is not meant in any way to prohibit normal interruptions inthe continuity of the process due to, for example, start-up, reactormaintenance, or scheduled shut down periods. The term “batch” process asused herein means a process wherein all the reactants are added to thereactor and then processed according to a predetermined course ofreaction during which no material is fed or removed from the reactor.The term “semicontinuous” means a process where some of the reactantsare charged at the beginning of the process and the remaining reactantsare fed continuously as the reaction progresses. Alternatively, asemicontinuous process may also include a process similar to a batchprocess in which all the reactants are added at the beginning of theprocess except that one or more of the products are removed continuouslyas the reaction progresses. The process is operated advantageously as acontinuous process for economic reasons and to produce superiorcoloration of the polymer as the sulfopolyester may deteriorate inappearance if allowed to reside in a reactor at an elevated temperaturefor too long a duration.

The sulfopolyesters can be prepared by procedures known to personsskilled in the art. The sulfomonomer is most often added directly to thereaction mixture from which the polymer is made, although otherprocesses are known and may also be employed, for example, as describedin U.S. Pat. No. 3,018,272, U.S. Pat. No. 3,075,952, and U.S. Pat. No.3,033,822. The reaction of the sulfomonomer, diol component, and thedicarboxylic acid component may be carried out using conventionalpolyester polymerization conditions. For example, when preparing thesulfopolyesters by means of an ester interchange reaction, i.e., fromthe ester form of the dicarboxylic acid components, the reaction processmay comprise two steps. In the first step, the diol component and thedicarboxylic acid component, such as, for example, dimethylisophthalate, are reacted at elevated temperatures of about 150° C. toabout 250° C. for about 0.5 to 8 hours at pressures ranging from about0.0 kPa gauge to about 414 kPa gauge (60 pounds per square inch,“psig”). Preferably, the temperature for the ester interchange reactionranges from about 180° C. to about 230° C. for about 1 to 4 hours whilethe preferred pressure ranges from about 103 kPa gauge (15 psig) toabout 276 kPa gauge (40 psig). Thereafter, the reaction product isheated under higher temperatures and under reduced pressure to form asulfopolyester with the elimination of a diol, which is readilyvolatilized under these conditions and removed from the system. Thissecond step, or polycondensation step, is continued under higher vacuumconditions and a temperature which generally ranges from about 230° C.to about 350° C., preferably about 250° C. to about 310° C., and mostpreferably about 260° C. to about 290° C. for about 0.1 to about 6hours, or preferably, for about 0.2 to about 2 hours, until a polymerhaving the desired degree of polymerization, as determined by inherentviscosity, is obtained. The polycondensation step may be conducted underreduced pressure which ranges from about 53 kPa (400 torr) to about0.013 kPa (0.1 torr). Stirring or appropriate conditions are used inboth stages to ensure adequate heat transfer and surface renewal of thereaction mixture. The reactions of both stages are facilitated byappropriate catalysts such as, for example, alkoxy titanium compounds,alkali metal hydroxides and alcoholates, salts of organic carboxylicacids, alkyl tin compounds, metal oxides, and the like. A three-stagemanufacturing procedure, similar to that described in U.S. Pat. No.5,290,631 may also be used, particularly when a mixed monomer feed ofacids and esters is employed.

To ensure that the reaction of the diol component and dicarboxylic acidcomponent by an ester interchange reaction mechanism is driven tocompletion, it is preferred to employ about 1.05 to about 2.5 moles ofdiol component to one mole of dicarboxylic acid component. Persons ofskill in the art will understand, however, that the ratio of diolcomponent to dicarboxylic acid component is generally determined by thedesign of the reactor in which the reaction process occurs.

In the preparation of sulfopolyester by direct esterification, i.e.,from the acid form of the dicarboxylic acid component, sulfopolyestersare produced by reacting the dicarboxylic acid or a mixture ofdicarboxylic acids with the diol component or a mixture of diolcomponents. The reaction is conducted at a pressure of from about 7 kPagauge (1 psig) to about 1,379 kPa gauge (200 psig), preferably less than689 kPa (100 psig) to produce a low molecular weight, linear or branchedsulfopolyester product having an average degree of polymerization offrom about 1.4 to about 10. The temperatures employed during the directesterification reaction typically range from about 180° C. to about 280°C., more preferably ranging from about 220° C. to about 270° C. This lowmolecular weight polymer may then be polymerized by a polycondensationreaction.

As noted hereinabove, the sulfopolyesters are advantageous for thepreparation of bicomponent and multicomponent fibers having a shapedcross section. We have discovered that sulfopolyesters or blends ofsulfopolyesters having a glass transition temperature (Tg) of at least35° C. are particularly useful for multicomponent fibers for preventingblocking and fusing of the fiber during spinning and take up. Further,to obtain a sulfopolyester with a Tg of at least 35° C., blends of oneor more sulfopolyesters may be used in varying proportions to obtain asulfopolyester blend having the desired Tg. The Tg of a sulfopolyesterblend may be calculated by using a weighted average of the Tg's of thesulfopolyester components. For example, sulfopolyesters having a Tg of48° C. may be blended in a 25:75 weight:weight ratio with anothersulfopolyester having Tg of 65° C. to give a sulfopolyester blend havinga Tg of approximately 61° C.

In another embodiment of the invention, the water dispersiblesulfopolyester component of the multicomponent fiber presents propertieswhich allow at least one of the following:

(a) the multicomponent fibers to be spun to a desired low denier,

(b) the sulfopolyester in these multicomponent fibers to be resistant toremoval during hydroentangling of a web formed from the multicomponentfibers but is efficiently removed at elevated temperatures afterhydroentanglement, and

(c) the multicomponent fibers to be heat settable so as to yield astable, strong fabric. Surprising and unexpected results were achievedin furtherance of these objectives using a sulfopolyester having acertain melt viscosity and level of sulfomonomer residues.

As previously discussed, the sulfopolyester or sulfopolyester blendutilized in the multicomponent fibers or binders can have a meltviscosity of generally less than about 12,000, 10,000, 6,000, or 4,000poise as measured at 240° C. and at a 1 rad/sec shear rate. In anotheraspect, the sulfopolyester or sulfopolyester blend exhibits a meltviscosity of between about 1,000 to 12,000 poise, more preferablybetween 2,000 to 6,000 poise, and most preferably between 2,500 to 4,000poise measured at 240° C. and at a 1 rad/sec shear rate. Prior todetermining the viscosity, the samples are dried at 60° C. in a vacuumoven for 2 days. The melt viscosity is measured on a rheometer using 25mm diameter parallel-plate geometry at a 1 mm gap setting. A dynamicfrequency sweep is run at a strain rate range of 1 to 400 rad/sec and 10percent strain amplitude. The viscosity is then measured at 240° C. andat a strain rate of 1 rad/sec.

The level of sulfomonomer residues in the sulfopolyester polymers is atleast 4 or 5 mole percent and less than about 25, 20, 12, or 10 molepercent, reported as a percentage of the total diacid or diol residuesin the sulfopolyester. Sulfomonomers for use with the inventionpreferably have 2 functional groups and one or more sulfonate groupsattached to an aromatic or cycloaliphatic ring wherein the functionalgroups are hydroxyl, carboxyl, or a combination thereof. Asodiosulfo-isophthalic acid monomer is particularly preferred.

In addition to the sulfomonomer described previously, the sulfopolyesterpreferably comprises residues of one or more dicarboxylic acids, one ormore diol residues wherein at least 25 mole percent, based on the totaldiol residues, is a poly(ethylene glycol) having a structureH—(OCH₂—CH₂)_(n)—OH wherein n is an integer in the range of 2 to about500, and 0 to about 20 mole percent, based on the total repeating units,of residues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof.

In a particularly preferred embodiment, the sulfopolyester comprisesfrom about 60 to 99, 80 to 96, or 88 to 94 mole percent of dicarboxylicacid residues, from about 1 to 40, 4 to 20, or 6 to 12 mole percent ofsulfomonomer residues, and 100 mole percent of diol residues (therebeing a total mole percent of 200 percent, i.e., 100 mole percent diacidand 100 mole percent diol). More specifically, the dicarboxylic portionof the sulfopolyester comprises between about 50 to 95, 60 to 80, or 65to 75 mole percent of terephthalic acid, about 0.5 to 49, 1 to 30, or 15to 25 mole percent of isophthalic acid, and about 1 to 40, 4 to 20, or 6to 12 mole percent of 5-sodiosulfoisophthalic acid (5-SSIPA). The diolportion comprises from about 0 to 50 mole percent of diethylene glycoland from about 50 to 100 mole percent of ethylene glycol. An exemplaryformulation according to this embodiment of the invention is set forthsubsequently.

TABLE 1 Approximate Mole percent (based on total moles of diol or diacidresidues) Terephthalic acid 71 Isophthalic acid 20 5-SSIPA 9 Diethyleneglycol 35 Ethylene glycol 65

The water dispersible component of the multicomponent fibers or thebinders of the nonwoven article may consist essentially of or, consistof, the sulfopolyesters described hereinabove. In another embodiment,however, the sulfopolyesters of this invention may be blended with oneor more supplemental polymers to modify the properties of the resultingmulticomponent fiber or nonwoven article. The supplemental polymer mayor may not be water-dispersible depending on the application and may bemiscible or immiscible with the sulfopolyester. If the supplementalpolymer is water non-dispersible, it is preferred that the blend withthe sulfopolyester is immiscible.

The term “miscible,” as used herein, is intended to mean that the blendhas a single, homogeneous amorphous phase as indicated by a singlecomposition-dependent Tg. For example, a first polymer that is misciblewith second polymer may be used to “plasticize” the second polymer asillustrated, for example, in U.S. Pat. No. 6,211,309. By contrast, theterm “immiscible,” as used herein, denotes a blend that shows at leasttwo randomly mixed phases and exhibits more than one Tg. Some polymersmay be immiscible and yet compatible with the sulfopolyester. A furthergeneral description of miscible and immiscible polymer blends and thevarious analytical techniques for their characterization may be found inPolymer Blends Volumes 1 and 2, Edited by D. R. Paul and C. B. Bucknall,2000, John Wiley & Sons, Inc, the disclosure of which is incorporatedherein by reference.

Non-limiting examples of water-dispersible polymers that may be blendedwith the sulfopolyester are polymethacrylic acid, polyvinyl pyrrolidone,polyethylene-acrylic acid copolymers, polyvinyl methyl ether, polyvinylalcohol, polyethylene oxide, hydroxy propyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose,isopropyl cellulose, methyl ether starch, polyacrylamides, poly(N-vinylcaprolactam), polyethyl oxazoline, poly(2-isopropyl-2-oxazoline),polyvinyl methyl oxazolidone, water-dispersible sulfopolyesters,polyvinyl methyl oxazolidimone, poly(2,4-dimethyl-6-triazinylethylene),and ethylene oxide-propylene oxide copolymers. Examples of polymerswhich are water non-dispersible that may be blended with thesulfopolyester include, but are not limited to, polyolefins, such ashomo- and copolymers of polyethylene and polypropylene; poly(ethyleneterephthalate); poly(butylene terephthalate); and polyamides, such asnylon-6; polylactides; caprolactone; Eastar Bio® (poly(tetramethyleneadipate-co-terephthalate), a product of Eastman Chemical Company);polycarbonate; polyurethane; and polyvinyl chloride.

According to our invention, blends of more than one sulfopolyester maybe used to tailor the end-use properties of the resulting multicomponentfiber or nonwoven article. The blends of one or more sulfopolyesterswill have Tg's of at least 25° C. for the binder compositions and atleast 35° C. for the multicomponent fibers.

The sulfopolyester and supplemental polymer may be blended in batch,semicontinuous, or continuous processes. Small scale batches may bereadily prepared in any high-intensity mixing devices well known tothose skilled in the art, such as Banbury mixers, prior to melt-spinningfibers. The components may also be blended in solution in an appropriatesolvent. The melt blending method includes blending the sulfopolyesterand supplemental polymer at a temperature sufficient to melt thepolymers. The blend may be cooled and pelletized for further use or themelt blend can be melt spun directly from this molten blend into fiberform. The term “melt” as used herein includes, but is not limited to,merely softening the polyester. For melt mixing methods generally knownin the polymers art, see Mixing and Compounding of Polymers (I.Manas-Zloczower & Z. Tadmor editors, Carl Hanser Verlag Publisher, 1994,New York, N.Y.).

The water non-dispersible components of the multicomponent fibers andthe nonwoven articles of this invention also may contain otherconventional additives and ingredients which do not deleteriously affecttheir end use. For example, additives include, but are not limited to,starches, fillers, light and heat stabilizers, antistatic agents,extrusion aids, dyes, anticounterfeiting markers, slip agents,tougheners, adhesion promoters, oxidative stabilizers, UV absorbers,colorants, pigments, opacifiers (delustrants), optical brighteners,fillers, nucleating agents, plasticizers, viscosity modifiers, surfacemodifiers, antimicrobials, antifoams, lubricants, thermostabilizers,emulsifiers, disinfectants, cold flow inhibitors, branching agents,oils, waxes, and catalysts.

In one embodiment of the invention, the multicomponent fibers andnonwoven articles will contain less than 10 weight percent ofanti-blocking additives, based on the total weight of the multicomponentfiber or nonwoven article. For example, the multicomponent fiber ornonwoven article may contain less than 10, 9, 5, 3, or 1 weight percentof a pigment or filler based on the total weight of the multicomponentfiber or nonwoven article. Colorants, sometimes referred to as toners,may be added to impart a desired neutral hue and/or brightness to thewater non-dispersible polymer. When colored fibers are desired, pigmentsor colorants may be included in the water non-dispersible polymer whenproducing the polymer or they may be melt blended with the preformedsulfopolyester. A preferred method of including colorants is to use acolorant having thermally stable organic colored compounds havingreactive groups such that the colorant is copolymerized and incorporatedinto the water non-dispersible polymer to improve its hue. For example,colorants such as dyes possessing reactive hydroxyl and/or carboxylgroups, including, but not limited to, blue and red substitutedanthraquinones, may be copolymerized into the polymer chain

As previously discussed, the segments or domains of the multicomponentfibers may comprise one or more water non-dispersible syntheticpolymers. Examples of water non-dispersible synthetic polymers which maybe used in segments of the multicomponent fiber include, but are notlimited to, polyolefins, polyesters, copolyesters, polyamides,polylactides, polycaprolactone, polycarbonate, polyurethane, acrylics,cellulose ester, and/or polyvinyl chloride. For example, the waternon-dispersible synthetic polymer may be polyester such as polyethyleneterephthalate, polyethylene terephthalate homopolymer, polyethyleneterephthalate copolymer, polybutylene terephthalate, polycyclohexylenecyclohexanedicarboxylate, polycyclohexylene terephthalate,polytrimethylene terephthalate, and the like. As In another example, thewater non-dispersible synthetic polymer can be biodistintegratable asdetermined by DIN Standard 54900 and/or biodegradable as determined byASTM Standard Method, D6340-98. Examples of biodegradable polyesters andpolyester blends are disclosed in U.S. Pat. No. 5,599,858; U.S. Pat. No.5,580,911; U.S. Pat. No. 5,446,079; and U.S. Pat. No. 5,559,171.

The term “biodegradable,” as used herein in reference to the waternon-dispersible synthetic polymers, is understood to mean that thepolymers are degraded under environmental influences such as, forexample, in a composting environment, in an appropriate and demonstrabletime span as defined, for example, by ASTM Standard Method, D6340-98,entitled “Standard Test Methods for Determining Aerobic Biodegradationof Radiolabeled Plastic Materials in an Aqueous or Compost Environment.”The water non-dispersible synthetic polymers of the present inventionalso may be “biodisintegratable,” meaning that the polymers are easilyfragmented in a composting environment as defined, for example, by DINStandard 54900. For example, the biodegradable polymer is initiallyreduced in molecular weight in the environment by the action of heat,water, air, microbes, and other factors. This reduction in molecularweight results in a loss of physical properties (tenacity) and often infiber breakage. Once the molecular weight of the polymer is sufficientlylow, the monomers and oligomers are then assimilated by the microbes. Inan aerobic environment, these monomers or oligomers are ultimatelyoxidized to CO₂, H₂O, and new cell biomass. In an anaerobic environment,the monomers or oligomers are ultimately converted to CO₂, H₂, acetate,methane, and cell biomass.

Additionally, the water non-dispersible synthetic polymers may comprisealiphatic-aromatic polyesters, abbreviated herein as “AAPE.” The term“aliphatic-aromatic polyester,” as used herein, means a polyestercomprising a mixture of residues from aliphatic dicarboxylic acids,cycloaliphatic dicarboxylic acids, aliphatic diols, cycloaliphaticdiols, aromatic diols, and aromatic dicarboxylic acids. The term“non-aromatic,” as used herein with respect to the dicarboxylic acid anddiol monomers of the present invention, means that carboxyl or hydroxylgroups of the monomer are not connected through an aromatic nucleus. Forexample, adipic acid contains no aromatic nucleus in its backbone (i.e.,the chain of carbon atoms connecting the carboxylic acid groups), thusadipic acid is “non-aromatic.” By contrast, the term “aromatic” meansthe dicarboxylic acid or diol contains an aromatic nucleus in itsbackbone such as, for example, terephthalic acid or 2,6-naphthalenedicarboxylic acid. “Non-aromatic,” therefore, is intended to includeboth aliphatic and cycloaliphatic structures such as, for example, diolsand dicarboxylic acids, which contain as a backbone a straight orbranched chain or cyclic arrangement of the constituent carbon atomswhich may be saturated or paraffinic in nature, unsaturated (i.e.,containing non-aromatic carbon-carbon double bonds), or acetylenic(i.e., containing carbon-carbon triple bonds). Thus, non-aromatic isintended to include linear and branched, chain structures (referred toherein as “aliphatic”) and cyclic structures (referred to herein as“alicyclic” or “cycloaliphatic”). The term “non-aromatic,” however, isnot intended to exclude any aromatic substituents which may be attachedto the backbone of an aliphatic or cycloaliphatic diol or dicarboxylicacid. In the present invention, the difunctional carboxylic acidtypically is a aliphatic dicarboxylic acid such as, for example, adipicacid, or an aromatic dicarboxylic acid such as, for example,terephthalic acid. The difunctional hydroxyl compound may becycloaliphatic diol such as, for example, 1,4-cyclohexanedimethanol, alinear or branched aliphatic diol such as, for example, 1,4-butanediol,or an aromatic diol such as, for example, hydroquinone.

The AAPE may be a linear or branched random copolyester and/or chainextended copolyester comprising diol residues which comprise theresidues of one or more substituted or unsubstituted, linear orbranched, diols selected from aliphatic diols containing 2 to 8 carbonatoms, polyalkylene ether glycols containing 2 to 8 carbon atoms, andcycloaliphatic diols containing about 4 to about 12 carbon atoms. Thesubstituted diols, typically, will comprise 1 to 4 substituentsindependently selected from halo, C₆-C₁₀ aryl, and C₁-C₄ alkoxy.Examples of diols which may be used include, but are not limited to,ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol,2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, polyethylene glycol, diethylene glycol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclo-hexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, triethylene glycol, andtetraethylene glycol. The AAPE also comprises diacid residues whichcontain about 35 to about 99 mole percent, based on the total moles ofdiacid residues, of the residues of one or more substituted orunsubstituted, linear or branched, non-aromatic dicarboxylic acidsselected from aliphatic dicarboxylic acids containing 2 to 12 carbonatoms and cycloaliphatic acids containing about 5 to 10 carbon atoms.The substituted non-aromatic dicarboxylic acids will typically contain 1to about 4 substituents selected from halo, C₆-C₁₀ aryl, and C₁-C₄alkoxy. Non-limiting examples of non-aromatic diacids include malonic,succinic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric,2,2-dimethyl glutaric, suberic, 1,3-cyclopentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, and 2,5-norbornane-dicarboxylic. In addition to thenon-aromatic dicarboxylic acids, the AAPE comprises about 1 to about 65mole percent, based on the total moles of diacid residues, of theresidues of one or more substituted or unsubstituted aromaticdicarboxylic acids containing 6 to about 10 carbon atoms. In the casewhere substituted aromatic dicarboxylic acids are used, they willtypically contain 1 to about 4 substituents selected from halo, C₆-C₁₀aryl, and C₁-C₄ alkoxy. Non-limiting examples of aromatic dicarboxylicacids which may be used in the AAPE of our invention are terephthalicacid, isophthalic acid, salts of 5-sulfoisophthalic acid, and2,6-naphthalenedicarboxylic acid. More preferably, the non-aromaticdicarboxylic acid will comprise adipic acid, the aromatic dicarboxylicacid will comprise terephthalic acid, and the diol will comprise1,4-butanediol.

Other possible compositions for the AAPE are those prepared from thefollowing diols and dicarboxylic acids (or polyester-forming equivalentsthereof such as diesters) in the following mole percentages, based on100 mole percent of a diacid component and 100 mole percent of a diolcomponent:

(1) glutaric acid (about 30 to about 75 mole percent), terephthalic acid(about 25 to about 70 mole percent), 1,4-butanediol (about 90 to 100mole percent), and modifying diol (0 about 10 mole percent);

(2) succinic acid (about 30 to about 95 mole percent), terephthalic acid(about 5 to about 70 mole percent), 1,4-butanediol (about 90 to 100 molepercent), and modifying diol (0 to about 10 mole percent); and

(3) adipic acid (about 30 to about 75 mole percent), terephthalic acid(about 25 to about 70 mole percent), 1,4-butanediol (about 90 to 100mole percent), and modifying diol (0 to about 10 mole percent).

The modifying diol preferably is selected from1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol, andneopentyl glycol. The most preferred AAPEs are linear, branched, orchain extended copolyesters comprising about 50 to about 60 mole percentadipic acid residues, about 40 to about 50 mole percent terephthalicacid residues, and at least 95 mole percent 1,4-butanediol residues.Even more preferably, the adipic acid residues comprise about 55 toabout 60 mole percent, the terephthalic acid residues comprise about 40to about 45 mole percent, and the diol residues comprise about 95 molepercent 1,4-butanediol residues. Such compositions are commerciallyavailable under the trademark EASTAR BIO® copolyester from EastmanChemical Company, Kingsport, Tenn., and under the trademark ECOFLEX®from BASF Corporation.

Additional, specific examples of preferred AAPEs include apoly(tetra-methylene glutarate-co-terephthalate) containing (a) 50 molepercent glutaric acid residues, 50 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues, (b) 60 molepercent glutaric acid residues, 40 mole percent terephthalic acidresidues, and 100 mole percent-1,4-butanediol residues, or (c) 40 molepercent glutaric acid residues, 60 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues; apoly(tetramethylene succinate-co-terephthalate) containing (a) 85 molepercent succinic acid residues, 15 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues or (b) 70 molepercent succinic acid residues, 30 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues; a poly(ethylenesuccinate-co-terephthalate) containing 70 mole percent succinic acidresidues, 30 mole percent terephthalic acid residues, and 100 molepercent ethylene glycol residues; and a poly(tetramethyleneadipate-co-terephthalate) containing (a) 85 mole percent adipic acidresidues, 15 mole percent terephthalic acid residues, and 100 molepercent 1,4-butanediol residues; or (b) 55 mole percent adipic acidresidues, 45 mole percent terephthalic acid residues, and 100 molepercent 1,4-butanediol residues.

The AAPE preferably comprises from about 10 to about 1,000 repeatingunits and preferably, from about 15 to about 600 repeating units. TheAAPE may have an inherent viscosity of about 0.4 to about 2.0 dL/g, ormore preferably about 0.7 to about 1.6 dL/g, as measured at atemperature of 25° C. using a concentration of 0.5 g copolyester in 100ml of a 60/40 by weight solution of phenol/tetrachloroethane.

The AAPE, optionally, may contain the residues of a branching agent. Themole percent ranges for the branching agent are from about 0 to about 2mole percent, preferably about 0.1 to about 1 mole percent, and mostpreferably about 0.1 to about 0.5 mole percent based on the total molesof diacid or diol residues (depending on whether the branching agentcontains carboxyl or hydroxyl groups). The branching agent preferablyhas a weight average molecular weight of about 50 to about 5,000, morepreferably about 92 to about 3,000, and a functionality of about 3 toabout 6. The branching agent, for example, may be the esterified residueof a polyol having 3 to 6 hydroxyl groups, a polycarboxylic acid having3 or 4 carboxyl groups (or ester-forming equivalent groups), or ahydroxy acid having a total of 3 to 6 hydroxyl and carboxyl groups. Inaddition, the AAPE may be branched by the addition of a peroxide duringreactive extrusion.

The water non-dispersible component of the multicomponent fiber maycomprise any of those water non-dispersible synthetic polymers describedpreviously. Spinning of the fiber may also occur according to any methoddescribed herein. However, the improved rheological properties of themulticomponent fibers in accordance with this aspect of the inventionprovide for enhanced drawings speeds. When the sulfopolyester and waternon-dispersible synthetic polymer are extruded to produce multicomponentextrudates, the multicomponent extrudate is capable of being melt drawnto produce the multicomponent fiber, using any of the methods disclosedherein, at a speed of at least about 2,000, 3,000, 4,000, or 4,500m/min. Although not intending to be bound by theory, melt drawing of themulticomponent extrudates at these speeds results in at least someoriented crystallinity in the water non-dispersible component of themulticomponent fiber. This oriented crystallinity can increase thedimensional stability of nonwoven materials made from the multicomponentfibers during subsequent processing.

Another advantage of the multicomponent extrudate is that it can be meltdrawn to a multicomponent fiber having an as-spun denier of less than15, 10, 5, or 2.5 deniers per filament.

Therefore, in another embodiment of the invention, a multicomponentextrudate having a shaped cross section, comprising:

(a) at least one water dispersible sulfopolyester; and (b) a pluralityof domains comprising one or more water non-dispersible syntheticpolymers immiscible with the sulfopolyester, wherein the domains aresubstantially isolated from each other by the sulfopolyester interveningbetween the domains, wherein the extrudate is capable of being meltdrawn at a speed of at least about 2000 m/min.

Optionally, the drawn fibers may be textured and wound-up to form abulky continuous filament. This one-step technique is known in the artas spin-draw-texturing. Other embodiments include flat filament(non-textured) yarns, or cut staple fiber, either crimped or uncrimped.

This invention can be further illustrated by the following examples ofembodiments thereof, although it will be understood that these examplesare included merely for the purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

EXAMPLES Example 1

A sulfopolyester polymer was prepared with the following diacid and diolcomposition: diacid composition (71 mole percent terephthalic acid, 20mole percent isophthalic acid, and 9 mole percent 5-(sodiosulfo)isophthalic acid) and diol composition (60 mole percent ethylene glycoland 40 mole percent diethylene glycol). The sulfopolyester was preparedby high temperature polyesterification under a vacuum. Theesterification conditions were controlled to produce a sulfopolyesterhaving an inherent viscosity of about 0.31. The melt viscosity of thissulfopolyester was measured to be in the range of about 3,000 to 4,000poise at 240° C. and 1 rad/sec shear rate.

Example 2

The sulfopolyester polymer of Example 1 was spun into bicomponentsegmented pie fibers and formed into a nonwoven web according to theprocedure described in Example 9 of U.S. 2008/0311815, hereinincorporated by reference. During the process, the primary extruder (A)fed Eastman F61HC PET polyester melt to form the larger segment slicesinto the segmented pie structure. The extrusion zones were set to meltthe PET entering the spinnerette die at a temperature of 285° C. Thesecondary extruder (B) processed the sulfopolyester polymer of Example1, which was fed at a melt temperature of 255° C. into the spinnerettedie. The melt throughput rate per hole was 0.6 gm/min. The volume ratioof PET to sulfopolyester in the bicomponent extrudates was set at 70/30,which represents the weight ratio of about 70/30. The cross-section ofthe bicomponent extrudates had wedge shaped domains of PET withsulfopolyester polymer separating these domains.

The bicomponent extrudates were melt drawn using the same aspiratorassembly used in Comparative Example 8 of U.S. 2008/0311815, hereinincorporated by reference. The maximum available pressure of the air tothe aspirator without breaking the bicomponent fibers during drawing was45 psi. Using 45 psi air, the bicomponent extrudates were melt drawndown to bicomponent fibers with as-spun denier of about 1.2 with thebicomponent fibers exhibiting a diameter of about 11 to 12 microns whenviewed under a microscope. The speed during the melt drawing process wascalculated to be about 4,500 m/min.

The bicomponent fibers were laid down into nonwoven webs having weightsof 140 gsm and 110 gsm. The shrinkage of the webs was measured byconditioning the material in a forced-air oven for five minutes at 120°C. The area of the nonwoven webs after shrinkage was about 29 percent ofthe webs' starting areas.

Microscopic examination of the cross section of the melt drawn fibersand fibers taken from the nonwoven web displayed a very good segmentedpie structure where the individual segments were clearly defined andexhibited similar size and shape. The PET segments were completelyseparated from each other so that they would form eight separate PETmonocomponent fibers having a pie-slice shape after removal of thesulfopolyester from the bicomponent fiber.

The nonwoven web, having a 110 gsm fabric weight, was soaked for eightminutes in a static deionized water bath at various temperatures. Thesoaked nonwoven web was dried and the percent weight loss due to soakingin deionized water at the various temperatures was measured as shown inTable 2.

TABLE 2 Soaking 36° C. 41° C. 46° C. 51° C. 56° C. 72° C. TemperatureNonwoven Web 1.1 2.2 14.4 25.9 28.5 30.5 Weight Loss

The sulfopolyester polymer dissipated very readily into deionized waterat temperatures above about 46° C., with the removal of thesulfopolyester polymer from the fibers being very extensive or completeat temperatures above 51° C. as shown by the weight loss. A weight lossof about 30 percent represented complete removal of the sulfopolyesterfrom the bicomponent fibers in the nonwoven web. If hydroentanglement isused to process this nonwoven web of bicomponent fibers comprising thissulfopolyester, it would be expected that the polymer would not beextensively removed by the hydroentangling water jets at watertemperatures below 40° C.

Example 3

The nonwoven webs of Example 2 having basis weights of both 140 gsm and110 gsm were hydroentangled using a hydroentangling apparatusmanufactured by Fleissner, GmbH, Egelsbach, Germany. The machine hadfive total hydroentangling stations wherein three sets of jets contactedthe top side of the nonwoven web and two sets of jets contacted theopposite side of the nonwoven web. The water jets comprised a series offine orifices about 100 microns in diameter machined in two-feet widejet strips. The water pressure to the jets was set at 60 bar (Jet Strip#1), 190 bar (Jet Strips #2 and 3), and 230 bar (Jet Strips #4 and 5).During the hydroentanglement process, the temperature of the water tothe jets was found to be in the range of about 40 to 45° C. The nonwovenfabric exiting the hydroentangling unit was strongly tied together. Thecontinuous fibers were knotted together to produce a hydroentanglednonwoven fabric with high resistance to tearing when stretched in bothdirections.

Next, the hydroentangled nonwoven fabric was fastened onto a tenterframe comprising a rigid rectangular frame with a series of pins aroundthe periphery thereof. The fabric was fastened to the pins to restrainthe fabric from shrinking as it was heated. The frame with the fabricsample was placed in a forced-air oven for three minutes at 130° C. tocause the fabric to heat set while being restrained. After heat setting,the conditioned fabric was cut into a sample specimen of measured sizeand the specimen was conditioned at 130° C. without restraint by atenter frame. The dimensions of the hydroentangled nonwoven fabric afterthis conditioning were measured and only minimal shrinkage (<0.5 percentreduction in dimension) was observed. It was apparent that heat settingof the hydroentangled nonwoven fabric was sufficient to produce adimensionally stable nonwoven fabric.

The hydroentangled nonwoven fabric, after being heat set as describedabove, was washed in 90° C. deionized water to remove the sulfopolyesterpolymer and leave the PET monocomponent fiber segments remaining in thehydroentangled fabric.

After repeated washings, the dried fabric exhibited a weight loss ofapproximately 26 percent. Washing the nonwoven web beforehydroentangling demonstrated a weight loss of 31.3 percent. Therefore,the hydroentangling process removed some of the sulfopolyester from thenonwoven web, but this amount was relatively small. In order to lessenthe amount of sulfopolyester removed during hydroentanglement, the watertemperature of the hydroentanglement jets should be lowered to below 40°C.

The sulfopolyester of Example 1 was found to produce segmented piefibers having good segment distribution wherein the waternon-dispersable polymer segments formed individual fibers of similarsize and shape after removal of the sulfopolyester polymer. The rheologyof the sulfopolyester was suitable to allow the bicomponent extrudatesto be melt drawn at high rates to achieve fine denier bicomponent fiberswith as-spun denier as low as about 1.0. These bicomponent fibers arecapable of being laid down into a nonwoven web, which could behydroentangled without experiencing significant loss of sulfopolyesterpolymer to produce the nonwoven fabric. The nonwoven fabric produced byhydroentangling the nonwoven web exhibited high strength and could beheat set at temperatures of about 120° C. or higher to produce anonwoven fabric with excellent dimensional stability. The sulfopolyesterpolymer was removed from the hydroentangled nonwoven fabric in a washingstep. This resulted in a strong nonwoven fabric product with a lighterfabric weight, greater flexibility, and softer hand. The PET microfibersin this nonwoven fabric product were wedge shaped and exhibited anaverage denier of about 0.1.

Example 4

A sulfopolyester polymer was prepared with the following diacid and diolcomposition: diacid composition (69 mole percent terephthalic acid, 22.5mole percent isophthalic 25 acid, and 8.5 mole percent 5-(sodiosulfo)isophthalic acid) and diol composition (65 mole percent ethylene glycoland 35 mole percent diethylene glycol). The sulfopolyester was preparedby high temperature polyesterification under a vacuum. Theesterification conditions were controlled to produce a sulfopolyesterhaving an inherent viscosity of about 0.33. The melt viscosity of thissulfopolyester was measured to be in the range of about 6000 to 7000poise at 240° C. and 1 rad/sec shear rate.

Example 5

The sulfopolyester polymer of Example 4 was spun into bicomponent fibershaving an islands-in-sea cross-section configuration with 16 islands ona spunbond line. The primary extruder (A) fed Eastman F61HC PETpolyester melt to form the islands in the islands-in-sea structure. Theextrusion zones were set to melt the PET entering the spinnerette die ata temperature of about 290° C. The secondary extruder (B) processed thesulfopolyester polymer of Example 4, which was fed at a melt temperatureof about 260° C. into the spinnerette die. The volume ratio of PET tosulfopolyester in the bicomponent extrudates was set at 70/30, whichrepresents the weight ratio of about 70/30. The melt throughput ratethrough the spinneret was 0.6 g/hole/minute. The cross-section of thebicomponent extrudates had round shaped island domains of PET withsulfopolyester polymer separating these domains.

The bicomponent extrudates were melt drawn using an aspirator assembly.The maximum available pressure of air to the aspirator without breakingthe bicomponent fibers during melt drawing was 50 psi. Using 50 psi air,the bicomponent extrudates were melt drawn down to bicomponent fiberswith an as-spun denier of about 1.4 with the bicomponent fibersexhibiting a diameter of about 12 microns when viewed under amicroscope. The speed during the drawing process was calculated to beabout 3,900 m/min.

Example 6

The sulfopolyester polymer of Example 4 was spun into bicomponentislands-in-the-sea cross-section fibers with 64 islands fibers using abicomponent extrusion line. The primary extruder (A) fed Eastman F61HCPET polyester melt to form the islands in the islands-in-the-sea fibercross-section structure. The secondary extruder (B) fed thesulfopolyester polymer melt to form the sea in the islands-in-seabicomponent fiber.

The inherent viscosity of polyester was 0.61 dL/g while the meltviscosity of the dry sulfopolyester was about 7,000 poise measured at240° C. and 1 rad/sec strain rate using the melt viscosity measurementprocedure described earlier. These islands-in-sea bicomponent fiberswere made using a spinneret with 198 holes and a throughput rate of 0.85gms/minute/hole. The polymer ratio between “islands” polyester and “sea”sulfopolyester was 65 percent to 35 percent. These bicomponent fiberswere spun using an extrusion temperature of 280° C. for the polyestercomponent and 260° C. for the sulfopolyester component. The bicomponentfiber contains a multiplicity of filaments (198 filaments) and was meltspun at a speed of about 530 meters/minute, forming filaments with anominal denier per filament of about 14. A finish solution of 24 weightpercent PT 769 finish from Goulston Technologies was applied to thebicomponent fiber using a kiss roll applicator. The filaments of thebicomponent fiber were then drawn in line using a set of two godetrolls, heated to 90° C. and 130° C. respectively, and the final drawroll operating at a speed of about 1,750 meters/minute, to provide afilament draw ratio of about 3.3× forming the drawn islands-in-seabicomponent filaments with a nominal denier per filament of about 4.5 oran average diameter of about 25 microns. These filaments comprised thepolyester microfiber “islands” having an average diameter of about 2.5microns.

Example 7

The drawn islands-in-sea bicomponent fibers of Example 6 were cut intoshort length fibers of 3.2 millimeters and 6.4 millimeters cut lengths,thereby producing short length bicomponent fibers with 64 islands-in-seacross-section configurations. These short cut bicomponent fiberscomprised “islands” of polyester and a “sea” of water dispersiblesulfopolyester polymer. The cross-sectional distribution of islands andsea was essentially consistent along the length of these short cutbicomponent fibers.

Example 8

The drawn islands-in-sea bicomponent fibers of Example 6 were soaked insoft water for about 24 hours and then cut into short length fibers of3.2 millimeters and 6.4 millimeters cut lengths. The water dispersiblesulfopolyester was at least partially emulsified prior to cutting intoshort length fibers. Partial separation of islands from the seacomponent was therefore effected, thereby producing partially emulsifiedshort length islands-in-sea bicomponent fibers.

Example 9

The short cut length islands-in-sea bicomponent fibers of Example 8 werewashed using soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby releasing the polyestermicrofibers which were the “islands” component of the bicomponentfibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers showed anaverage diameter of about 2.5 microns and lengths of 3.2 and 6.4millimeters.

Comparative Example 10

Wet-laid hand sheets were prepared using the following procedure: 7.5gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A., and 188 gms of roomtemperature water were placed in a 1,000 ml pulper and pulped for 30seconds at 7,000 rpm to produce a pulped mixture. This pulped mixturewas transferred into an 8 liter metal beaker along with 7,312 grams ofroom temperature water to make about 0.1 percent consistency (7,500 gmswater and 7.5 gms fibrous material) pulp slurry. This pulp slurry wasagitated using a high speed impeller mixer for 60 seconds. Procedure tomake the hand sheet from this pulp slurry was as follows. The pulpslurry was poured into a 25 centimeters×30 centimeters hand sheet moldwhile continuing to stir. The drop valve was pulled, and the pulp fiberswere allowed to drain on a screen to form a hand sheet. 750 grams persquare meter (gsm) blotter paper was placed on top of the formed handsheet, and the blotter paper was flattened onto the hand sheet. Thescreen frame was raised and inverted onto a clean release paper andallowed to sit for 10 minutes. The screen was raised vertically awayfrom the formed hand sheet. Two sheets of 750 gsm blotter paper wereplaced on top of the formed hand sheet. The hand sheet was dried alongwith the three blotter papers using a Norwood Dryer at about 88° C. for15 minutes. One blotter paper was removed leaving one blotter paper oneach side of the hand sheet. The hand sheet was dried using a WilliamsDryer at 65° C. for 15 minutes. The hand sheet was then further driedfor 12 to 24 hours using a 40 kg dry press. The blotter paper wasremoved to obtain the dry hand sheet sample. The hand sheet was trimmedto 21.6 centimeters by 27.9 centimeters dimensions for testing.

Comparative Example 11

Wet-laid hand sheets were prepared using the following procedure: 7.5gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A., 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, and 188 gms of room temperature water were placed in a1,000 ml pulper and pulped for 30 seconds at 7,000 rpm to produce apulped mixture. This pulped mixture was transferred into an 8 litermetal beaker along with 7,312 gms of room temperature water to makeabout 0.1 percent consistency (7,500 gms water and 7.5 gms fibrousmaterial) to produce a pulp slurry. This pulp slurry was agitated usinga high speed impeller mixer for 60 seconds. The rest of procedure formaking hand sheet from this pulp slurry was same as in ComparativeExample 10.

Example 12

Wet-laid hand sheets were prepared using the following procedure. 6.0gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A., 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, 1.5 gms of 3.2 millimeter cut length islands-in-seafibers of Example 7 and 188 gms of room temperature water were placed ina 1,000 ml pulper and pulped for 30 seconds at 7,000 rpm to produce afiber mix slurry. This fiber mix slurry was heated to 82° C. for 10seconds to emulsify and remove the water dispersible sulfopolyestercomponent in the islands-in-sea fibers and release the polyestermicrofibers. The fiber mix slurry was then strained to produce asulfopolyester dispersion comprising the sulfopolyester and amicrofiber-containing mixture comprising pulp fibers and polyestermicrofiber. The microfiber-containing mixture was further rinsed using500 gms of room temperature water to further remove the waterdispersible sulfopolyester from the microfiber-containing mixture. Thismicrofiber-containing mixture was transferred into an 8 liter metalbeaker along with 7,312 gms of room temperature water to make about 0.1percent consistency (7,500 gms water and 7.5 gms fibrous material) toproduce a microfiber-containing slurry. This microfiber-containingslurry was agitated using a high speed impeller mixer for 60 seconds.The rest of procedure for making hand sheet from thismicrofiber-containing slurry was same as in Comparative Example 10.

Comparative Example 13

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of MicroStrand 475-106 micro glass fiber available from JohnsManville, Denver, Colo., U.S.A., 0.3 gms of Solivitose N pre-gelatinizedquaternary cationic potato starch from Avebe, Foxhol, the Netherlands,and 188 gms of room temperature water were placed in a 1,000 ml pulperand pulped for 30 seconds at 7,000 rpm to produce a glass fiber mixture.This glass fiber mixture was transferred into an 8 liter metal beakeralong with 7,312 gms of room temperature water to make about 0.1 percentconsistency (7,500 gms water and 7.5 gms fibrous material) to produce aglass fiber slurry. This glass fiber slurry was agitated using a highspeed impeller mixer for 60 seconds. The rest of procedure for makinghand sheet from this glass fiber slurry was same as in ComparativeExample 10.

Example 14

Wet-laid hand sheets were prepared using the following procedure. 3.8gms of MicroStrand 475-106 micro glass fiber available from JohnsManville, Denver, Colo., U.S.A., 3.8 gms of 3.2 millimeter cut lengthislands-in-sea fibers of Example 7, 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, and 188 gms of room temperature water were placed in a1,000 ml pulper and pulped for 30 seconds at 7,000 rpm to produce afiber mix slurry. This fiber mix slurry was heated to 82° C. for 10seconds to emulsify and remove the water dispersible sulfopolyestercomponent in the islands-in-sea bicomponent fibers and release polyestermicrofibers. The fiber mix slurry was then strained to produce asulfopolyester dispersion comprising the sulfopolyester and amicrofiber-containing mixture comprising glass microfibers and polyestermicrofiber. The microfiber-containing mixture was further rinsed using500 gms of room temperature water to further remove the sulfopolyesterfrom the microfiber-containing mixture. This microfiber-containingmixture was transferred into an 8 liter metal beaker along with 7,312gms of room temperature water to make about 0.1 percent consistency(7,500 gms water and 7.5 gms fibrous material) to produce amicrofiber-containing slurry. This microfiber-containing slurry wasagitated using a high speed impeller mixer for 60 seconds. The rest ofprocedure for making hand sheet from this microfiber-containing slurrywas same as in Comparative Example 10.

Example 15

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of 3.2 millimeter cut length islands-in-sea fibers of Example 7, 0.3gms of Solivitose N pre-gelatinized quaternary cationic potato starchfrom Avebe, Foxhol, the Netherlands, and 188 gms of room temperaturewater were placed in a 1,000 ml pulper and pulped for 30 seconds at7,000 rpm to produce a fiber mix slurry. This fiber mix slurry washeated to 82° C. for 10 seconds to emulsify and remove the waterdispersible sulfopolyester component in the islands-in-sea fibers andrelease polyester microfibers. The fiber mix slurry was then strained toproduce a sulfopolyester dispersion and polyester microfibers. Thesulfopolyester dispersion was comprised of water dispersiblesulfopolyester. The polyester microfibers were rinsed using 500 gms ofroom temperature water to further remove the sulfopolyester from thepolyester microfibers. These polyester microfibers were transferred intoan 8 liter metal beaker along with 7,312 gms of room temperature waterto make about 0.1 percent consistency (7,500 gms water and 7.5 gmsfibrous material) to produce a microfiber slurry. This microfiber slurrywas agitated using a high speed impeller mixer for 60 seconds. The restof procedure for making hand sheet from this microfiber slurry was sameas in Comparative Example 10.

The hand sheet samples of Examples 10-15 were tested and properties areprovided in Table 3.

TABLE 3 Hand Porosity Basis Sheet Greiner Tensile Elongation ExampleWeight Thickness Density (seconds/ Strength to Break Tensile × NumberComposition (gsm) (mm) (gm/cc) 100 cc) (kg/15 mm) (%) Elongation 10 100%SBSK 94 0.45 0.22 4 1.0 7 7 11 SBSK + 4% Starch 113 0.44 0.22 4 1.5 7 1112 80SBSK + 116 0.30 0.33 4 2.2 9 20 Starch + 20% 3.2 mm polyestermicrofibers of Example 9 13 100% Glass 103 0.68 0.15 4 0.2 15 3MicroStrand 475-106 + Starch 14 50% Glass 104 0.45 0.22 4 1.4 7 10Microstand 475-106 + 50% 3.2 mm polyester microfibers of Example 9 +Starch 15 100% 3.2 mm 80 0.38 0.26 4 3.0 15 44 polyester microfibers ofExample 9

The hand sheet basis weight was determined by weighing the hand sheetand calculating weight in grams per square meter (gsm). Hand sheetthickness was measured using an Ono Sokki EG-233 thickness gauge andreported as thickness in millimeters. Density was calculated as weightin grams per cubic centimeter. Porosity was measured using a GreinerPorosity Manometer with 1.9×1.9 cm² opening head and 100 cc capacity.Porosity is reported as average time in seconds (4 replicates) for 100cc of water to pass through the sample. Tensile properties were measuredusing an Instron Model TM for six 30 mm×105 mm test strips. An averageof six measurements is reported for each example. It can be observedfrom these test results that significant improvement in tensileproperties of wet-laid fibrous structures is obtained by the addition ofpolyester microfibers of the current invention.

Example 16

The sulfopolyester polymer of Example 4 was spun into bicomponentislands-in-the-sea cross-section fibers with 37 islands using abicomponent extrusion line. The primary extruder (A) fed Eastman F61HCPET polyester to form the “islands” in the islands-in-the-seacross-section structure. The secondary extruder (B) fed the waterdispersible sulfopolyester polymer to form the “sea.” The inherentviscosity of the polyester was 0.61 dL/g while the melt viscosity of thedry sulfopolyester was about 7,000 poise measured at 240° C. and 1rad/sec strain rate using the melt viscosity measurement proceduredescribed previously. These islands-in-sea bicomponent fibers were madeusing a spinneret with 72 holes and a throughput rate of 1.15gms/minute/hole. The polymer ratio between “islands” polyester and “sea”sulfopolyester was 2 to 1. These bicomponent fibers were spun using anextrusion temperature of 280° C. for the polyester component and 255° C.for the water dispersible sulfopolyester component. This bicomponentfiber contained a multiplicity of filaments (198 filaments) and was meltspun at a speed of about 530 meters/minute forming filaments with anominal denier per filament of 19.5. A finish solution of 24 percent byweight PT 769 finish from Goulston Technologies was applied to thebicomponent fiber using a kiss roll applicator. The filaments of thebicomponent fiber were then drawn in line using a set of two godetrolls, heated to 95° C. and 130° C., respectively, and the final drawroll operating at a speed of about 1,750 meters/minute, to provide afilament draw ratio of about 3.3× forming the drawn islands-in-seabicomponent filaments with a nominal denier per filament of about 5.9 oran average diameter of about 29 microns. These filaments comprising thepolyester microfiber islands had an average diameter of about 3.9microns.

Example 17

The drawn islands-in-sea bicomponent fibers of Example 16 were cut intoshort length bicomponent fibers of 3.2 millimeters and 6.4 millimeterscut length, thereby, producing short length fibers with 37islands-in-sea cross-section configurations. These fibers comprised“islands” of polyester and a “sea” of water dispersible sulfopolyesterpolymers. The cross-sectional distribution of “islands” and “sea” wasessentially consistent along the length of these bicomponent fibers.

Example 18

The short cut length islands-in-sea fibers of Example 17 were washedusing soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby releasing the polyestermicrofibers which were the “islands” component of the bicomponentfibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers had anaverage diameter of about 3.9 microns and lengths of 3.2 and 6.4millimeters.

Example 19

The sulfopolyester polymer of Example 4 was spun into bicomponentislands-in-the-sea cross-section fibers with 37 islands using abicomponent extrusion line. The primary extruder (A) fed polyester toform the “islands” in the islands-in-the-sea fiber cross-sectionstructure. The secondary extruder (B) fed the water dispersiblesulfopolyester polymer to form the “sea” in the islands-in-seabicomponent fiber. The inherent viscosity of the polyester was 0.52 dL/gwhile the melt viscosity of the dry water dispersible sulfopolyester wasabout 3,500 poise measured at 240° C. and 1 rad/sec strain rate usingthe melt viscosity measurement procedure described previously. Theseislands-in-sea bicomponent fibers were made using two spinnerets with175 holes each and a throughput rate of 1.0 gms/minute/hole. The polymerratio between the “islands” polyester and “sea” sulfopolyester was 70percent to 30 percent. These bicomponent fibers were spun using anextrusion temperature of 280° C. for the polyester component and 255° C.for the sulfopolyester component. The bicomponent fibers contained amultiplicity of filaments (350 filaments) and were melt spun at a speedof about 1,000 meters/minute using a take-up roll heated to 100° C.forming filaments with a nominal denier per filament of about 9 and anaverage fiber diameter of about 36 microns. A finish solution of 24weight percent PT 769 finish was applied to the bicomponent fiber usinga kiss roll applicator. The filaments of the bicomponent fiber werecombined and were then drawn 3.0× on a draw line at draw roll speed of100 m/minute and temperature of 38° C. forming drawn islands-in-seabicomponent filaments with an average denier per filament of about 3 andaverage diameter of about 20 microns. These drawn island-in-seabicomponent fibers were cut into short length fibers of about 6.4millimeters length. These short length islands-in-sea bicomponent fiberswere comprised of polyester microfiber “islands” having an averagediameter of about 2.8 microns.

Example 20

The short cut length islands-in-sea bicomponent fibers of Example 19were washed using soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby releasing the polyestermicrofibers which were the “islands” of the fibers. The washed polyestermicrofibers were rinsed using soft water at 25° C. to essentially removemost of the “sea” component. The optical microscopic observation ofwashed fibers showed polyester microfibers of average diameter of about2.8 microns and lengths of about 6.4 millimeters.

Example 21

Wet-laid microfiber stock hand sheets were prepared using the followingprocedure. 56.3 gms of 3.2 millimeter cut length islands-in-seabicomponent fibers of Example 6, 2.3 gms of Solivitose N pre-gelatinizedquaternary cationic potato starch from Avebe, Foxhol, the Netherlands,and 1,410 gms of room temperature water were placed in a 2 liter beakerto produce a fiber slurry. The fiber slurry was stirred. One quarteramount of this fiber slurry, about 352 ml, was placed in a 1,000 mlpulper and pulped for 30 seconds at 7,000 rpm. This fiber slurry washeated to 82° C. for 10 seconds to emulsify and remove the waterdispersible sulfopolyester component in the islands-in-sea bicomponentfibers and release the polyester microfibers. The fiber slurry was thenstrained to produce a sulfopolyester dispersion and polyestermicrofibers. These polyester microfibers were rinsed using 500 gms ofroom temperature water to further remove the sulfopolyester from thepolyester microfibers. Sufficient room temperature water was added toproduce 352 ml of microfiber slurry. This microfiber slurry wasre-pulped for 30 seconds at 7,000 rpm. These microfibers weretransferred into an 8 liter metal beaker. The remaining three quartersof the fiber slurry were similarly pulped, washed, rinsed, re-pulped,and transferred to the 8 liter metal beaker. 6,090 gms of roomtemperature water was then added to make about 0.49 percent consistency(7,500 gms water and 36.6 gms of polyester microfibers) to produce amicrofiber slurry. This microfiber slurry was agitated using a highspeed impeller mixer for 60 seconds. The rest of procedure for makinghand sheet from this microfiber slurry was same as in ComparativeExample 10. The microfiber stock hand sheet with the basis weight ofabout 490 gsm was comprised of polyester microfibers of average diameterof about 2.5 microns and average length of about 3.2 millimeters.

Example 22

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of polyester microfiber stock hand sheet of Example 21, 0.3 gms ofSolivitose N pre-gelatinized quaternary cationic potato starch fromAvebe, Foxhol, the Netherlands, and 188 gms of room temperature waterwere placed in a 1,000 ml pulper and pulped for 30 seconds at 7,000 rpm.The microfibers were transferred into an 8 liter metal beaker along with7,312 gms of room temperature water to make about 0.1 percentconsistency (7,500 gms water and 7.5 gms fibrous material) to produce amicrofiber slurry. This microfiber slurry was agitated using a highspeed impeller mixer for 60 seconds. The rest of procedure for makinghand sheet from this slurry was same as in Comparative Example 10. A 100gsm wet-laid hand sheet of polyester microfibers was obtained having anaverage diameter of about 2.5 microns.

Example 23

The 6.4 millimeter cut length islands-in-sea bicomponent fibers ofExample 19 were washed using soft water at 80° C. to remove the waterdispersible sulfopolyester “sea” component, thereby releasing thepolyester microfibers which were the “islands” component of thebicomponent fibers. The washed polyester microfibers were rinsed usingsoft water at 25° C. to essentially remove most of the “sea” component.The optical microscopic observation of the washed polyester microfibersshowed an average diameter of about 2.5 microns and lengths of 6.4millimeters.

Example 24

The short cut length islands-in-sea bicomponent fibers of Example 6,Example 16, and Example 19 were washed separately using soft water at80° C. containing about 1 percent by weight based on the weight of thebicomponent fibers of ethylene diamine tetra acetic acid tetra sodiumsalt (Na₄ EDTA) from Sigma-Aldrich Company, Atlanta, Ga., to remove thewater dispersible sulfopolyester “sea” component, thereby releasing thepolyester microfibers which were the “islands” of the bicomponentfibers. The addition of at least one water softener, such as Na₄ EDTA,aids in the removal of the water dispersible sulfopolyester polymer fromthe islands-in-sea bicomponent fibers. The washed polyester microfiberswere rinsed using soft water at 25° C. to essentially remove most of the“sea” component. The optical microscopic observation of washed polyestermicrofibers showed excellent release and separation of polyestermicrofibers. Use of a water softening agent such as Na₄ EDTA in thewater prevents any Ca⁺⁺ ion exchange on the sulfopolyester, which canadversely affect the water dispersiblity of sulfopolyester. Typical softwater may contain up to 15 ppm of Ca⁺⁺ ion concentration. It isdesirable that the soft water used in the processes described hereshould have essentially zero concentration of Ca⁺⁺ and othermulti-valent ions, or alternately, use sufficient amount of watersoftening agent, such as Na₄ EDTA, to bind the Ca⁺⁺ ions and othermulti-valent ions. These polyester microfibers can be used in preparingthe wet-laid sheets using the procedures of examples disclosedpreviously.

Example 25

The short cut length islands-in-sea bicomponent fibers of Example 6 andExample 16 were processed separately using the following procedure: 17grams of Solivitose N pre-gelatinized quaternary cationic potato starchfrom Avebe, Foxhol, the Netherlands, were added to distilled water.After the starch was fully dissolved or hydrolyzed, then 429 grams ofshort cut length islands-in-sea bicomponent fibers were slowly added tothe distilled water to produce a fiber slurry. A Williams RotaryContinuous Feed Refiner (5 inch diameter) was turned on to refine or mixthe fiber slurry in order to provide sufficient shearing action for thewater dispersible sulfopolyester to be separated from the polyestermicrofibers. The contents of the stock chest were poured into a 24 literstainless steel container and the lid was secured. The stainless steelcontainer was placed on a propane cooker and heated until the fiberslurry began to boil at about 97° C. in order to remove thesulfopolyester component in the island-in-sea fibers and releasepolyester microfibers. After the fiber slurry reached boiling, it wasagitated with a manual agitating paddle. The contents of the stainlesssteel container were poured into a 27 in×15 in×6 in deep False BottomKnuche with a 30 mesh screen to produce a sulfopolyester dispersion andpolyester microfibers. The sulfopolyester dispersion comprised water andwater dispersible sulfopolyester. The polyester microfibers were rinsedin the Knuche for 15 seconds with 10 liters of soft water at 17° C., andsqueezed to remove excess water.

After removing excess water, 20 grams of polyester microfiber (dry fiberbasis) was added to 2,000 ml of water at 70° C. and agitated using a 2liter 3000 rpm ¾ horse power hydropulper manufactured by HermannManufacturing Company for 3 minutes (9,000 revolutions) to make amicrofiber slurry of 1 percent consistency. Handsheets were made usingthe procedure described previously in Comparative Example 10.

The optical and scanning electron microscopic observation of thesehandsheets showed excellent separation and formation of polyestermicrofibers.

Example 26

The sulfopolyester polymer of Example 4 was spun into bicomponentislands-in-the-sea cross-section fibers with 37 islands using abicomponent extrusion line. The primary extruder (A) fed Eastman F61HCPET polyester to form the “islands” in the islands-in-the-seacross-section structure. The secondary extruder (B) fed the waterdispersible sulfopolyester polymer to form the “sea” in theislands-in-sea bicomponent fiber. The inherent viscosity of thepolyester was 0.61 dL/g while the melt viscosity of the drysulfopolyester was about 7,000 poise measured at 240° C. and 1 rad/secstrain rate using the melt viscosity measurement procedure describedpreviously. These islands-in-sea bicomponent fibers were made using aspinneret with 72 holes. The polymer ratio between “islands” polyesterand “sea” sulfopolyester was 2.33 to 1.

These bicomponent fibers were spun using an extrusion temperature of280° C. for the polyester component and 255° C. for the waterdispersible sulfopolyester component. This bicomponent fiber contained amultiplicity of filaments (198 filaments) and was melt spun at a speedof about 530 meters/minute, forming filaments with a nominal denier perfilament of 19.5. A finish solution of 18 percent by weight PT 769finish from Goulston Technologies was applied to the bicomponent fiberusing a kiss roll applicator. The filaments of the bicomponent fiberwere then drawn in line using a set of two godet rolls, heated to 95° C.and 130° C., respectively, and the final draw roll operating at a speedof about 1,750 meters/minute to provide a filament draw ratio of about3.3×, thus forming the drawn islands-in-sea bicomponent filaments with anominal denier per filament of about 3.2. These filaments comprised thepolyester microfiber islands having an average diameter of about 2.2microns.

Example 27

The drawn islands-in-sea bicomponent fibers of Example 26 were cut intoshort length bicomponent fibers of 1.5 millimeters cut length, therebyproducing short length fibers with 37 islands-in-sea cross-sectionconfigurations. These fibers comprised “islands” of polyester and a“sea” of water dispersible sulfopolyester polymers. The cross-sectionaldistribution of “islands” and “sea” was essentially consistent along thelength of these bicomponent fibers.

Example 28

The short cut length islands-in-sea fibers of Example 27 were washedusing soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby releasing the polyestermicrofibers which were the “islands” component of the bicomponentfibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers had anaverage diameter of about 2.2 microns and a length of 1.5 millimeters.

Example 29

Wet-laid hand sheets were prepared using the following procedure. Twograms total of a mixture of MicroStrand 475-106 glass fiber and thepolyester microfiber of Example 28 were added to 2,000 ml of water andagitated using a modified blender for 1 to 2 minutes in order to make amicrofiber slurry of 0.1 percent consistency. The pulp slurry was pouredinto a 25 centimeters×30 centimeters hand sheet mold while continuing tostir. The drop valve was pulled, and the pulp fibers were allowed todrain on a screen to form a hand sheet. 750 grams per square meter (gsm)blotter paper was placed on top of the formed hand sheet, and theblotter paper was flattened onto the hand sheet. The screen frame wasraised and inverted onto a clean release paper and allowed to sit for 10minutes. The screen was raised vertically away from the formed handsheet. Two sheets of 750 gsm blotter paper were placed on top of theformed hand sheet. The hand sheet was dried along with the three blotterpapers using a Norwood Dryer at about 88° C. for 15 minutes. One blotterpaper was removed leaving one blotter paper on each side of the handsheet. The hand sheet was dried using a Williams Dryer at 65° C. for 15minutes. The hand sheet was then further dried for 12 to 24 hours usinga 40 kg dry press. The blotter paper was removed to obtain the dry handsheet sample. The hand sheet was trimmed to 21.6 centimeters by 27.9centimeters dimensions for testing. Table 3 describes the physicalcharacteristics of the resulting wet-laid nonwoven media. Corestaporosity and average pore size when reported in these examples weredetermined using a QuantaChrome Porometer 3G Micro obtained fromQuantaChrome Instruments located in Boynton Beach, Fla.

TABLE 4 wt % Tensile Pressure synthetic wt % glass strength Coresta dropAverage pore Filtration Sample ¹ microfiber ² microfiber ³ (kg/15 mm)porosity (mm H₂O) size (microns) efficiency 1 100 0 0.88 388 8 7.4 71.0% 2 60 40 0.77 288 32 5.0  99.97% 3 40 60 0.71 176 44 3.8 99.999% 40 100 0.58 132 55 3.2 99.999% ¹ 80 gram per square meter ² 2.2 micron indiameter, 1.5 mm in length synthetic microfibers of Example 28 ³Johns-Manville Microstrand 106X (0.65 micron BET average diameter)

Example 30

Wet-laid hand sheets were prepared using the following procedure: 1.2grams of MicroStrand 475-106 glass fiber and 0.8 grams of the polyestermicrofiber of Example 28 (dry fiber basis) were added to 2,000 ml ofwater and agitated using a modified blender for 1 to 2 minutes to make amicrofiber slurry of 0.1 percent consistency. Handsheets were made usingthe procedure described previously in Comparative Example 10. Theresulting handsheets were evaluated for filtration efficiency byexposing the substrate to an aerosol of sodium chloride particles(number average diameter 0.075 micron, mass average diameter 0.26micron). A filtration efficiency of 99.999 percent was measured. Thisdata indicates that ULPA filtration efficiency can be obtained byutilizing the polymeric microfibers of the invention.

Comparative Example 31

Wet-laid hand sheets were prepared using the following procedure: 1.2grams of MicroStrand 475-106 glass fiber and 0.8 grams of MicroStrand475-110× glass fiber (both available from Johns Manville, Denver, Colo.,USA) were added to 2,000 ml of water and agitated using a modifiedblender for 1 to 2 minutes to make a glass microfiber slurry of 0.1percent consistency. Handsheets were made using the procedure describedpreviously in Example 29.

Example 32

The wet-laid handsheets of Samples 2 and 3 from Example 29 andComparative Example 31 were subjected to a calendaring process whichinvolved passing the handsheets between two stainless steel rolls with anip pressure of 300 pounds per linear inch. Due to the fragile nature ofits 100 percent glass composition, the handsheets of Comparative Example31 were destroyed in the calendaring process with the remaining sheetfragments turning essentially to glass powder with even minimal physicalhandling. The glass/polyester microfiber blends of Samples 2 and 3 fromExample 29, when calendared, yielded very uniform nonwoven sheets withsignificant mechanical integrity and flexibility. It was observed thatthe calendared nonwoven sheet of Sample 2 of Example 29 was somewhatstronger than the calendared nonwoven sheet of Sample 3 of Example 29.These data suggests that very durable, high efficiency filtration mediacan be enabled by the polymeric microfibers of the invention.

Example 33

Handsheets of Sample 1 of Example 29 were mechanically densified bysubjecting them to different pressures via a calendaring process. Theeffect of this densification is demonstrated below in Table 5 andclearly indicates that significant improvements to pore size andporosity can be made when the wet-laid substrates are calendared, whichis a design feature which Example 32 indicates cannot be accomplishedwith media comprised of 100 percent glass fibers.

TABLE 5 Calendar Pressure Average pore Coresta Sample (psig) size(microns) porosity 1  0 9.3 —² 2 100 7.6 —² 3 200 7.3 —² 4 400 4.5 268 5500 3.9 176 HEPA¹ — 3.9 255 ¹commercial HEPA filtration media ²could notbe measured as samples did not fit test unit

Example 34

Wet-laid hand sheets were prepared using the following procedure: 0.4grams of 3 denier per filament PET fibers cut to 12.7 millimeters and1.6 grams of the polyester microfiber of Example 28 (dry fiber basis)were added to 2,000 ml of water and agitated using a modified blenderfor 1 to 2 minutes to make a microfiber slurry of 0.1 percentconsistency. Handsheets were made using the procedure describedpreviously in Comparative Example 10. A series of polymeric binders (asdescribed in the table below) were applied to these handsheets at a rateof 7 percent binder based on the dry weight of nonwoven sheet. Thebinder-containing nonwoven sheets were dried in a forced air oven at 63°C. for 7 to 12 minutes and then heat-set at 120° C. for 3 minutes. Thefinal basis weight of the binder-containing nonwoven sheets was 90 g/m².The data indicates the significant strength benefits to be obtained bycombining a polymeric binder with the polymeric microfibers of theinvention.

TABLE 6 Dry Wet Tensile Tensile Tear Hercules Sam- Polymer (kg/ (kg/Force³ Burst⁴ Size⁵ ple Binder 15 mm) 15 mm) (grams) (psig) (seconds) Anone 0.6 0.6 201 5 4 B Synthomer 1.3 0.8 411 47 2 7100¹ C Eastek 3.8 2.9521 76 9 1100² D Eastek 3.5 3.2 516 82 150 1200² ¹Synthomer 7100 is astyrenic latex binder supplied by Synthomer GmbH, Frankfurt, Germany²Eastek 1100 and Eastek 1200 are sulfopolyester binder dispersionssupplied by Eastman Chemical Company, Kingsport, TN, USA ³as measured byINDA/EDANA test method WSP 100.1 5 ⁴as measured by INDA/EDANA testmethod WSP 110.5 ⁵as measured by TAPPI test method T 530 OM07

Example 35

Samples C and D of Example 34 were reproduced with the addition to thesulfopolyester binder dispersion of triethyl citrate (TEC) as aplasticizer. The amount of TEC added to the sulfopolyester binderdispersion was 7.5 and 15 weight percent plasticizer based on totalweight of sulfopolyester.

TABLE 7 Dry Wet Tensile Tensile Tear Average Sam- Polymer (kg/ (kg/Force³ Pore size ple Binder 15 mm) 15 mm) (grams) (microns) Porosity AEastek 3.8 2.9 521 12 596 1100 B Eastek 2.7 2.5 641 6.4 660 1100 with7.5% TEC C Eastek 2.3 2.6 546 8.8 664 1100 with 15% TEC D Eastek 3.5 3.2516 10 480 1200 E Eastek 2.7 2.7 476 7.1 588 1200 with 7.5% TEC F Eastek2.8 3.2 601 6.4 568 1200 with 15% TEC

Example 36

Wet-laid handsheets were prepared as described for Sample D of Example34 with the exception that the handsheets were not subjected to theheat-setting condition of 120° C. for three minutes.

Example 37

The handsheets of Example 35 and Sample D of Example 34 were subjectedto the following test procedure in order to simulate a paper repulpingprocess. Two liters of room temperature tap water were added to a 2liter 3,000 rpm ¾ Hp hydropulper tri-rotor with 6 in diameter×10 inheight brass pulper (manufactured by Hermann Manufacturing Companyaccording to TAPPI 10 Standards). Two one-inch square samples of thenonwoven sheet to be tested were added to the water in the hydropulper.The squares were pulped for 500 revolutions at which time thehydropulper was stopped and the status of the squares of nonwoven sheetevaluated. If the squares were not completely disintegrated to theirconstituent fibers, the squares were pulped for an additional 500revolutions, and re-evaluated. This process was continued until thesquares had completely disintegrated to their constituent fibers atwhich time the test was concluded and the total number of revolutionswas recorded. The nonwoven squares from Sample D of Example 34 had notcompletely disintegrated after 15,000 revolutions. The nonwoven squaresof Example 34 were completely disintegrated to their constituent fibersafter 5,000 revolutions. This data suggests that readilyrepulpable/recyclable nonwoven sheets can be prepared from the polymericmicrofibers of the invention with the appropriate binder selection andheat treatment.

Example 38

The processes outlined in Examples 26-28 were modified by increasing thenominal denier of the bicomponent fiber of Example 26 such that the endresult following the process steps of Examples 27 and 28 was a short-cutpolyester microfiber with a diameter of 4.0 microns and a length of 1.5mm. These short-cut microfibers were blended at varying ratios with the2.2 micron diameter and 1.5 mm in length short cut microfibers describedin Example 28. 80 gram per square meter handsheets were prepared fromthese microfiber blends as outlined in Example 29. The ability topredictably control both pore size and porosity of a wet-laid nonwovenby blending synthetic microfibers with different diameters is clearlydemonstrated in the table below.

TABLE 8 Wt % 2.2 micron Average Pore Sample¹ synthetic fiber² PorositySize (microns) 1 20 1548 6.5 2 40 1280 8.2 3 60 1080 8.6 4 80 760 10.3 5100 488 10.8 ¹80 gram per square meter handsheets with no binder²synthetic microfibers of Example 28

Example 39

Following the procedure as outlined in Example 29, handsheets wereprepared which comprised ternary mixtures of the synthetic polyestermicrofibers of Example 28, Lyocell nano-fibrillated cellulosic fibers,and T043 polyester fiber (a 7 micron diameter 5.0 mm in length PETfiber). The characteristics of these wet-laid nonwovens are describedbelow.

TABLE 9 wt % Lyocell nano- wt % wt % fibrillated T043 Tensile syntheticcellulosic polyester strength Burst Sample¹ microfiber fiber² fiber³(kg/15 mm) (psig) 1 40 60 0 15 2.0 2 40 55 5 15 2.6 3 40 40 20 38 3.1¹80 gram per square meter, 7percentSynthomer 7100 binder supplied bySynthomer GmbH, Frankfurt, Germany ²2.2 micron in diameter, 1.5 mm inlength synthetic microfibers of Example 28 ³Lenzing

Example 40

Wet-laid hand sheets were prepared using the following procedure. 1.6grams of the polyester microfiber of Example 28 and 0.4 grams of 3.0dpf, ½ inch long PET staple fibers were added to 2,000 ml of water andagitated using a modified blender for 1 to 2 minutes in order to make amicrofiber slurry of 0.1 percent consistency. The pulp slurry was pouredinto a 25 centimeters×30 centimeters hand sheet mold while continuing tostir. The drop valve was pulled, and the pulp fibers were allowed todrain on a screen to form a hand sheet. 750 grams per square meter (gsm)blotter paper was placed on top of the formed hand sheet, and theblotter paper was flattened onto the hand sheet. The screen frame wasraised and inverted onto a clean release paper and allowed to sit for 10minutes. The screen was raised vertically away from the formed handsheet. Two sheets of 750 gsm blotter paper were placed on top of theformed hand sheet. The hand sheet was dried along with the three blotterpapers using a Norwood Dryer at about 88° C. for 15 minutes. One blotterpaper was removed leaving one blotter paper on each side of the handsheet. The hand sheet was dried using a Williams Dryer at 65° C. for 15minutes. The hand sheet was then further dried for 12 to 24 hours usinga 40 kg dry press. The blotter paper was removed to obtain the dry handsheet sample. The hand sheet was then trimmed for binder application.

The binding material was then added as follows. A powder-coated steelcoating board (with dried latex layer) having greater than 45-dynesurface energy was used. One side of the formed handsheet was coatedwith binding material, and then the other side was coated with bindingmaterial. Using a syringe, dilution water was added to the area on thesteel coating board corresponding to the size of the handsheet. Dilutionwater in an amount sufficient to fully but not excessively wet the firstside of the handsheet was added to the steel coating board. Using asyringe, binding material in an amount based on the dry weight desiredwas added to the dilution water on the steel coating board. The amountof binding material added is a function of the density of the sheet. Alower density non-woven sheet generally requires a greater percentage ofbinding material than a higher density non-woven sheet. The total amountof binding material to be added was split, and fifty percent of theamount was added to the dilution water for the first side.

The dilution water and the binding material were then spread out tocompletely pool the correct-size area on the steel coating board. Thehandsheet was positioned over the correct size area and allowed togently settle in the liquid to coat the first side. After 30-60 secondsof settling into the liquid, the handsheet was removed from the liquid.

Using a syringe, dilution water in an amount sufficient to fully but notexcessively wet the second side of the handsheet was added to thecorrect size area on the steel coating board. Using a syringe, theremaining fifty percent of the binding material was added to thedilution water for the second side on the steel coating board. Thedilution water and the binding material were then spread out tocompletely pool the correct size area on the steel coating board. Thehandsheet was inverted, positioned over the correct size area andallowed to gently settle in the liquid to coat the second side. After60-180 seconds of settling into the liquid, the handsheet was removedfrom the liquid. A 12 mm glass lab rod was used to roll the bindingmaterial into the handsheet interior, as needed.

The coated handsheet was then placed on a sheet of foil-backed releasepaper on a tray. The coated handsheet, the foil-backed release paper andthe tray were placed in a forced air oven at 145° F. for two minutes.The handsheet was then flipped and returned to the forced air oven at145° F. The handsheet was then removed from the forced air oven, and asheet of foil-backed release paper was placed on each side (i.e., thetop and bottom) of the handsheet. The handsheet with a sheet offoil-backed release paper on each of the top and bottom was then placedin a Norwood handsheet dryer. The screen was locked and the handsheetwith a sheet of foil-backed release paper on each of the top and bottomwas dried at 250° F. for three minutes

Utilizing the procedure outlined above, a series of aqueous dispersionsof polymeric binders were applied handsheets comprised of theaforementioned 80/20 blend of synthetic polyester microfiber of Example28 and 3 dpf, ½ inch PET fibers at a level to yield a 7% binder level(based on total weight of solid binder and fiber) in a 90 gram persquare meter nonwoven. Both the polymeric binders and thecharacteristics of the nonwovens resulting from their application aredescribed in Table 10 below.

TABLE 10 Tensile Strength Tear Avg. Polymeric (kg/15 mm) Strength BurstPore Size Sample Binder Dry Wet (grams) (psig) (microns) Porosity 1(comp.) none 0.6 0.6 201 5 7.8 552 2 Eastek 1100 ¹ 3.8 2.9 521 76 12.0596 3 Eastek 1200 ¹ 3.5 3.2 516 82 10.0 480 4 Eastek 1400 ¹ 2.1 1.9 42974 10.3 544 5 (comp.) Synthomer 7100 ² 1.3 0.8 411 47 7.3 476 ¹sulfopolyester dispersions available from Eastman Chemical Company ² ABSlatex available from Dow Chemical Company

Example 41

Samples 2 and 3 of Example 40 were reproduced with the addition to thesulfopolyester binder dispersion of triethyl citrate (TEC) as aplasticizer. The amount of TEC added to the sulfopolyester binderdispersion was 7.5 and 15 weight percent plasticizer based on totalweight of sulfopolyester. The characteristics of the resulting nonwovenhandsheets are described in Table 11.

TABLE 11 Dry Wet Tensile Tensile Tear Average Sam- Polymer (kg/ (kg/Force³ Pore size ple Binder 15 mm) 15 mm) (grams) (microns) Porosity 1Eastek 3.8 2.9 521 12 596 1100 2 Eastek 2.7 2.5 641 6.4 660 1100 with7.5% TEC 3 Eastek 2.3 2.6 546 8.8 664 1100 with 15% TEC 4 Eastek 3.5 3.2516 10 480 1200 5 Eastek 2.7 2.7 476 7.1 588 1200 with 7.5% TEC 6 Eastek2.8 3.2 601 6.4 568 1200 with 15% TEC

Example 42

Wet-laid handsheets were prepared as described for Sample 4 of Example41 with the exception that the handsheets were not subjected to theheat-setting condition of 120° C. for three minutes.

Example 43

The handsheets of Example 42 and Sample 4 of Example 41 were subjectedto the following test procedure in order to simulate a paper repulpingprocess. Two liters of room temperature tap water were added to a 2liter 3,000 rpm ¾ Hp hydropulper tri-rotor with 6 in diameter×10 inheight brass pulper (manufactured by Hermann Manufacturing Companyaccording to TAPPI 10 Standards). Two one-inch square samples of thenonwoven sheet to be tested were added to the water in the hydropulper.The squares were pulped for 500 revolutions at which time thehydropulper was stopped and the status of the squares of nonwoven sheetevaluated. If the squares were not completely disintegrated to theirconstituent fibers, the squares were pulped for an additional 500revolutions, and re-evaluated. This process was continued until thesquares had completely disintegrated to their constituent fibers atwhich time the test was concluded and the total number of revolutionswas recorded. The nonwoven squares from Sample 4 of 41 had notcompletely disintegrated after 15,000 revolutions. The nonwoven squaresof Example 42 were completely disintegrated to their constituent fibersafter 5,000 revolutions. This data suggests that readilyrepulpable/recyclable nonwoven sheets can be prepared from the polymericmicrofibers of the invention with the appropriate binder selection andheat treatment.

Example 44

Following the procedures outlined in Example 40, handsheets comprising100% of the synthetic polyester microfiber of Example 28 were preparedand aqueous dispersions of polymer binders were applied to thehandsheets at varying rates to yield final nonwoven articles with abasis weight of 80 grams per square meter. Both the polymeric bindersand the characteristics of the nonwovens resulting from theirapplication are described in Table 12 below.

TABLE 12 Tensile Avg. Polymeric Strength Tear Pore Binder (kg/15 mm)Strength Burst Size Sample and % Dry Wet (grams) (psig) (microns)Porosity  1 (comp.) none 0.1 0.2  50 2 6.9 574  2 Eastek 1100 - 7.5% ¹2.6 1.1 332 49 6.6 460  3 Eastek 1100 - 15.0% ¹ 3.4 2.2 225 54 7.0 489 4 Eastek 1100 - 22.5% ¹ 4.7 3.7 189 54 7.3 329  5 Eastek 1200 - 7.5% ¹2.0 1.4 288 37 6.3 576  6 Eastek 1200 - 15.0% ¹ 4.2 3.0 201 46 6.4 393 7 Eastek 1200 - 22.5% ¹ 4.6 5.0 175 42 10.0 357  8 (comp.) Synthomer7100 - 7.5% ² 0.9 1.1 237 10 5.9 409  9 (comp.) Synthomer 7100 - 22.5% ²1.2 1.8 315 51 6.2 353 10 (comp.) Lubrizol 26469 - 7.5% ³ 0.8 0.5 226 107.3 500 11 (comp.) Lubrizol 26469 - 15.0% ³ 1.0 0.5 338 17 6.8 471 12(comp.) Lubrizol 26469 - 22.5% ³ 1.4 0.7 333 25 6.8 412 ¹ sulfopolyesterdispersions available from Eastman Chemical Company ² ABS latexavailable from Dow Chemical Company ³ acrylic latex available fromLubrizol Corporation

The preferred forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Modifications to theexemplary embodiments, set forth above, could be readily made by thoseskilled in the art without departing from the spirit of the presentinvention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as it pertains to any apparatus not materiallydeparting from but outside the literal scope of the invention as setforth in the following claims.

1. A nonwoven article comprising a plurality of thermoplasticpolycondensate fibers and a sulfopolyester binder, wherein saidthermoplastic polycondensate fibers make up at least 10 weight percentof the total fiber content of said nonwoven article, wherein saidsulfopolyester binder makes up at least 1 weight percent and not morethan 40 weight percent of said nonwoven article, wherein said nonwovenarticle further comprises a plurality of synthetic microfibers having alength of less than 25 millimeters and a minimum transverse dimension ofless than 5 microns, wherein said synthetic microfibers make up at least1 weight percent of said nonwoven article.
 2. The nonwoven article ofclaim 1, wherein said synthetic microfibers are formed of athermoplastic polycondensate material so that said synthetic microfibersmake up at least a portion of said thermoplastic polycondensate fibers.3. The nonwoven article of claim 2, wherein said synthetic microfibersmake up at least 5, 10, or 20 weight percent and/or not more than 90,80, or 70 weight percent of said thermoplastic polycondensate fibers. 4.The nonwoven article of claim 2, wherein said thermoplasticpolycondensate material comprises a polyester and/or a polyamide.
 5. Thenonwoven article of claim 2, wherein said thermoplastic polycondensatematerial comprises polyethylene terephthlate homopolymer, polyethyleneterephthalate copolymers, polypropylene terephthalate, polybutyleneterephthalate, nylon 6, and/or nylon
 66. 6. The nonwoven article ofclaim 1, wherein said thermoplastic polycondensate fibers make up atleast 10, 20, 30, 40, 50, or 60 weight percent of the total fibercontent of said nonwoven article.
 7. The nonwoven article of claim 1,wherein said synthetic microfibers have a length of at least 0.25, 0.5,1.0 millimeter and/or not more than 25, 10, or 2 millimeters.
 8. Thenonwoven article of claim 1, wherein said synthetic microfibers areformed from multicomponent fibers having said synthetic fiber segmentssubstantially isolated from one another by a water dispersiblecomponent.
 9. The nonwoven article of claim 8, wherein said syntheticmicrofibers are formed by removing said water dispersible component fromsaid multicomponent fibers.
 10. The nonwoven article of claim 9, whereinsaid synthetic microfibers are formed by cutting said multicomponentfibers to the length of said synthetic microfibers prior to removal ofsaid water dispersible component.
 11. The nonwoven article of claim 1,wherein said sulfopolyester binder makes up at least 1, 2, or 4 weightpercent and/or not more than 40, 30, or 20 weight percent of saidnonwoven article.
 12. The nonwoven article of claim 1, wherein saidnonwoven article comprises said synthetic microfibers in an amount of atleast 20, 40, or 50 weight percent and/or not more than 90, 85, or 80weight percent, wherein said nonwoven article comprises saidsulfopolyester binder in an amount of at least 1, 2, or 4 weight percentand/or not more than 40, 30, or 20 weight percent.
 13. The nonwovenarticle of claim 1, wherein said nonwoven article comprises saidsynthetic microfibers in an amount of at least 1, 3, or 5 weight percentand/or not more than 25, 20, 15, or 10 weight percent, wherein saidnonwoven article comprises said sulfopolyester binder in an amount of atleast 1, 2, or 4 weight percent and/or not more than 40, 30, or 20weight percent.
 14. The nonwoven article of claim 1, wherein saidsulfopolyester binder contains substantially equimolar proportions ofacid moiety repeating units (100 mole percent) to hydroxy moietyrepeating units (100 mole percent), wherein the said sulfopolyesterbinder comprises repeating units of components (a), (b), (c) and (d) asfollows, wherein all stated mole percentages are based on the total ofall acid and hydroxy moiety repeating units being equal to 200 molepercent: (a) at least 50, 70, or 80 mole percent and/or not more than99, 96, or 94 mole percent isophthalic acid, (b) at least 1, 4, or 6mole percent and/or not more than 50, 30, or 20 mole percent5-sulfoisophthalic acid, (c) at least 20, 35, or 45 mole percent and/ornot more than 95, 85, or 80 mole percent 1,4-cyclohexanedimethanol; and(d) at least 5, 15, or 20 mole percent and/or not more than 80, 65, or55 mole percent diethylene glycol and/or ethylene glycol.
 15. Thenonwoven article of claim 1, wherein said sulfopolyester bindercomprises a blend of at least a first sulfopolyester and a secondsulfopolyester.
 16. The nonwoven article of claim 15, wherein said firstsulfopolyester is hydrophilic and said second sulfopolyester ishydrophobic.
 17. The nonwoven article of claim 15, wherein said firstsulfopolyester comprises repeating units of components (a), (b), (c) and(d) as follows, wherein all stated mole percentages are based on thetotal of all acid and hydroxy moiety repeating units being equal to 200mole percent: (a) at least 70, 75, or 80 mole percent and/or not morethan 90, 88, or 86 mole percent isophthalic acid, (b) at least 10, 12,or 16 mole percent and/or not more than 30, 25, or 20 mole percent5-sulfoisophthalic acid, (c) at least 25, 35, or 45 mole percent and/ornot more than 70, 60, or 55 mole percent 1,4-cyclohexanedimethanol; and(d) at least 30, 40, or 45 mole percent and/or not more than 75, 65, or55 mole percent diethylene glycol and/or ethylene glycol and whereinsaid second sulfopolyester comprises repeating units of components (a),(b), (c) and (d) as follows, wherein all stated mole percentages arebased on the total of all acid and hydroxy moiety repeating units beingequal to 200 mole percent: (a) at least 80, 85, or 88 mole percentand/or not more than 98, 96, or 93 mole percent isophthalic acid, (b) atleast 2, 4, or 7 mole percent and/or not more than 20, 15, or 12 molepercent 5-sulfoisophthalic acid, (c) at least 40, 50, 60 mole percentand/or not more than 95, 85, or 80 mole percent1,4-cyclohexanedimethanol; and (d) at least 5, 15, or 20 mole percentand/or not more than 50, 40, or 30 mole percent diethylene glycol and/orethylene glycol.
 18. The nonwoven article of claim 1, wherein saidnonwoven article further comprises a coating selected from the groupconsisting of a decorative coating, a printing ink, a barrier coating,an adhesive coating, and a heat seal coating.
 19. The nonwoven articleof claim 1, wherein said nonwoven article is selected from the groupconsisting of filter media, battery separators, personal hygienearticles, sanitary napkins, tampons, diapers, disposable wipes, flexiblepackaging, geotextiles, building and construction materials, surgicaland medical material, security papers, cardboard, recycled cardboard,synthetic leather and suede, automotive headliners, personal protectivegarments, acoustical media, concrete reinforcement, flexible perform forcompression molded composites, electrical materials, catalytic supportmembranes, thermal insulation, labels, food packaging material, printingand publishing papers.
 20. The nonwoven article of claim 1, wherein saidnonwoven article is produced by a dry-laid process or wet-laid process.